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Celestial revolutionary : Copernicus, the man and his universe

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In the spring of 1500, at the apex of the Renaissance, a papal secretary to the Borgia Pope, Alexander VI, wrote that ""All the world is in Rome."" Though no one knew it at the time, this included a young scholar by the name of Nicolaus Copernicus who would one day change the world.

One of the greatest polymaths of his or any age - linguist, lawyer, doctor, diplomat, politician, mathematician, scientist, astronomer, artist, cleric - Copernicus gave the world arguably the most important scientific discovery of the modern era: that earth and the planets revolve around the sun and that the earth rotates on its axis once every 24 hours. His heliocentric theory and the discoveries that would follow ushered in the age of modern astronomy, often called the Copernican Age, and change the way we look at the universe forever.

Here, for the first time, is a biography of Copernicus that not only describes his theories but the life of the man himself and the epic, thrilling times in which he lived.

Year:
2014
Publisher:
I.B. Tauris
Language:
english
Pages:
288
ISBN 10:
0857734903
ISBN 13:
978-0-85773-490-7
File:
PDF, 4.24 MB

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You can write a book review and share your experiences. Other readers will always be interested in your opinion of the books you've read. Whether you've loved the book or not, if you give your honest and detailed thoughts then people will find new books that are right for them.
John Freely was born in New York in 1926 and joined the US Navy at the
age of 17, serving during the last two years of World War II. He has a PhD
in physics from New York University and did postdoctoral studies in the history of science at Oxford. He is Professor of Physics at Bosphorus University
in Istanbul, where he has taught physics and the history of science since
1960. He has also taught in New York, Boston, London and Athens. He has
written more than 40 books, including works on the history of science and
travel. His most recent books on the history of science are Flame of Miletus:
The Birth of Science in Ancient Greece (2012) and Light from the East: How the
Science of Medieval Islam Helped to Shape the Western World (2011). His recent
books on history and travel include The Grand Turk, Storm on Horseback,
Children of Achilles, The Cyclades, The Ionian Islands (all I.B.Tauris), Crete, The
Western Shores of Turkey, Strolling Through Athens, Strolling Through Venice and
the bestselling Strolling Through Istanbul (all Tauris Parke Paperbacks).

To my beloved Toots.

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Figure 1 Nicolaus Copernicus, from the 1554 Paris edition of his biography by
Pierre Gassendi, presumably based on the self-portrait mentioned by Stimmer.

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Celestial
Revolutionary
Copernicus,
the Man
and
His Universe

JOHN FREELY

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Published in 2014 by I.B.Tauris & Co Ltd
6 Salem Road, London W2 4BU
175 Fifth Avenue, New York NY 10010
www.ibtauris.com
Distributed in the United States and Canada
Exclusively by Palgrave Macmillan
175 Fifth Avenue, New York NY 10010
Copyright © 2014 John Freely
The right of John Freely to be identified as the author of this work has been asserted by him
in accordance with the Copyright, Designs and Patents Act 1988.
All rights reserved. Except for brief quotations in a review, this book, or any part thereof,
may not be reproduced, stored in or introduce; d into a retrieval system, or transmitted, in
any form or by any means, electronic, mechanical, photocopying, recording or otherwise,
without the prior written permission of the publisher.
Every attempt has been made to gain permission for the use of the images in this book.
Any omissions will be rectified in future editions.
ISBN: 978 1 78076 350 7
eISBN: 978 0 85773 490 7
A full CIP record for this book is available from the British Library
A full CIP record is available from the Library of Congress
Library of Congress Catalog Card Number: available
Typeset by Newgen Publishers, Chennai
Printed and bound in Sweden by ScandBook AB

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CONTENTS

List of Illustrations
Introduction

vi
vii

1 ‘This Remote Corner of the Earth’

1

2 A New Age

13

3 The Jagiellonian University of Krakow

37

4 Renaissance Italy

53

5 The Bishopric of Warmia

65

6 The Little Commentary

75

7 The Letter Against Werner

85

8 The Frauenburg Wenches

99

9 The First Disciple

115

10 The First Account

131

11 Preparing the Revolutions

147

12 The Revolutions of the Celestial Spheres

163

13 The Copernican Revolution

185

14 Debating the Copernican and Ptolemaic Models

205

15 The Newtonian Synthesis

225

Epilogue Searching for Copernicus

245

Source Notes
Bibliography

251
265
275

Index

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ILLUSTRATIONS

1. Nicolaus Copernicus, from the 1554 Paris edition of his
biography by Pierre Gassendi, presumably based on the
self-portrait mentioned by Stimmer

ii

2. The apparent motion of the Sun through the constellations
Aries and Taurus (above); the apparent motion of Mars
through the constellations Aries and Taurus (below)

18

3. Epicycle model for explaining the apparent retrograde motion
of the planets (above); Ptolemy’s equant model (below)

25

4. Aristotle’s geocentric theory, Peter Apian, Cosmographica, 1539
(above); the Copernican heliocentric theory, De revolutionibus,
1543 (below)

94

5. The precession of the equinoxes (above); Copernican lunar
model (middle); Copernican model for the solar anomaly
(below) of a superior planet (left) and an inferior planet (right)

177

6. The Tychonic system (above); Kepler’s first two laws of
planetary motion (below)

193

7. Galileo’s observations of the Moon with the telescope, from
Siderius nuncius (The Starry Messenger), 1610

211

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INTRODUCTION

This is a biography of the Polish astronomer Nicolaus Copernicus (1473–
1543), who at the dawn of the Renaissance proposed the revolutionary
theory that the earth and the other planets were in orbit around the sun,
breaking with the geocentric cosmology that had been the world view since
antiquity.
The heliocentric theory, as it was called, was published in 1543, just
before Copernicus’ death. His book is entitled De revolutionibus orbium
coelestium libri VI (Six Books Concerning the Revolutions of the Heavenly
Spheres), a truly revolutionary work whose reverberations were felt far
beyond the realm of astronomy. During the first century after its publication, the Copernican theory was accepted by only a few astronomers, most
notably Kepler and Galileo, but their new sun-centred astronomy sparked
the seventeenth-century Scientific Revolution that climaxed with the new
world system of Isaac Newton, the beginning of modern science.
Despite its great importance De revolutionibus appeared in only two editions, the first in 1543 and the second in 1566, and it was not translated
into English until 1952, the year after I began earning my living as a physicist. Though his De revolutionibus has been called ‘the book that nobody
read,’ it changed our view of the universe forever, breaking the bounds of
the finite geocentric cosmos of antiquity and opening the way to the infinite and expanding universe of the new millennium.

vii

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CHAPTER 1

‘This Remote
Corner of the
Earth’

Sigismondo de’ Conti, the papal secretary, noted in his chronicle during the spring of 1500 that ‘All the world is in Rome.’ A few days before
Christmas 1499 Pope Alexander VI Borgia had declared that the following year would be a Jubilee, a period of special solemnity, in accordance
with the decree published in 1471 by Pope Paul II which declared that
each 25th year of the Christian era should be celebrated thusly. A special indulgence would be granted to all pilgrims who came to Rome and
visited the four principal churches of the city, beginning with St Peter’s,
whose doors would be open night and day throughout the Jubilee. The
celebrations went on throughout the year, and on Easter Sunday an
estimated 200,000 pilgrims thronged St Peter’s Square for the Pope’s
blessing. The pious monk Petrus Delphinus was led to exclaim ‘God be
praised, who has brought hither so many witnesses to the faith.’
Among the pilgrims was a young student named Nicolaus Copernicus,
who had come from Poland to Italy in the autumn of 1496 to enrol in
the faculty of law at the University of Bologna. The Italian Renaissance
was in full bloom and Copernicus was in Rome at the height of its glory,
before returning home the following year. He came back to Italy later
that year to study medicine at the University of Padua for two years,
before going to the University of Ferrara, where in 1503 he received a
doctorate in law. He then returned to what he later called ‘this remote

1

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CELESTIAL REVOLUTIONARY

corner of the earth,’ in present-day northern Poland, where he would
remain for the rest of his days.
One of the earliest biographies of Copernicus, a somewhat unreliable work in Latin published in 1654 by the French philosopher and
astronomer Pierre Gassendi, gives his name as Nicolai Copernici, one
of many forms that appear in various sources, including the astronomer’s own correspondence, Nicolaus Copernicus being the one now
generally used.
Copernicus was born on 19 February 1473 in a house on Saint Anne’s
Street in Thorn (Torun), a town on the Vistula, 110 miles south of
Danzig (Gdansk) and 110 miles northwest of Warsaw, in what was then
Royal Prussia, a region of the Kingdom of Poland. He was named after
his father, Niklas Koppernigk, but afterwards followed the academic
custom of the time and Latinized his name as Nicolaus Copernicus.
The Koppernigk family were originally German-speakers who
migrated eastward to the province of Silesia in the thirteenth century,
settling in the town known today as Koperniki, in present-day southeast
Poland, close to the Czech border. Around 1350 the family moved to
Krakow, capital of the Kingdom of Poland, where Niklas Koppernigk,
the astronomer’s great-great grandfather, was made a citizen in 1396.
The astronomer’s father, also named Niklas Koppernigk, first appears
in records in 1448 as a prosperous merchant dealing in copper, which
he sold mostly in Danzig, the Polish port city at the mouth of the Vistula.
Around 1458 he moved from Krakow to Thorn, where a few years later
he married Barbara, daughter of Lucas Watzenrode the Elder, a wealthy
merchant and city councillor.
The Watzenrodes also originated from Silesia, having taken their
name from their native village of Weizenrodau near Schweidnitz, which
they left for Thorn after 1360. Lucas Watzenrode the Elder was born in
Thorn in 1400 and in 1436 he married Katherina von Rüdiger. Katherina
was a widow, having previously been married to Henrich Pechau, a
town councillor of Thorn, by whom she had a son, Johann Peckau, who
would be like another uncle to the young Nicolaus Copernicus.
Lucas Watzenrode the Elder died in 1462, leaving three children:
Barbara, the astronomer’s mother; Christina, who in 1459 married
Tiedeman Van Allen, a prosperous merchant serving in the last quarter
of the fifteenth century eight one-year terms as Mayor of Thorn; and
Lucas Watzenrode the Younger, who would become Bishop of Warmia

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OF THE

EARTH’

(Ermeland), the region between Pomerania and Masuria in northeastern Poland, one of the four provinces into which the Duchy of Prussia
was then divided, with the Estates of Royal Prussia to its west and the
Kingdom of Poland to its south. The Watzenrodes were further related
by marriage to wealthy burgher families of Krakow, Danzig and Thorn,
as well as prominent noble families of Royal Prussia.
Thorn was founded on the site of an old Polish settlement by the
Teutonic Knights, who built a castle there in 1230. Three years later the
Grand Master of the Teutonic Knights, Hermann von Salza, together
with his associate Hermann Balk, signed the foundation charters for
Thorn and the nearby city of Kulm (Chelmno). These were among the
seventy places or more in Prussia founded by the Teutonic Knights, each
being protected by a castle and often endowed with a church. The sense
of security given by these castellated settlements attracted the surrounding farmers, and soon developed into towns and cities with craftsmen
and traders, each of the communities surrounded by defence walls and
interconnected by roads.
The Teutonic Knights were one of three orders – the others being
the Knights Templars and the Knights Hospitallers of St John – founded
during The Crusades, their purpose being to aid Christian pilgrims to
the Holy Land by building hospices and hospitals for them as well as
fighting alongside the crusaders. Their emblem, a black cross on a white
field, contrasted with the red cross on white of the Knights Templars
and the white cross on red of the Knights Hospitallers.
The Order of the Teutonic Knights was founded at the end of the
twelfth century at Acre in the Gulf of Haifa, which had been captured
by the army of the Third Crusade in 1191 after a memorable siege.
Following the defeat of the Christian forces in the Levant, the Order
moved to Transylvania in 1211 to help defend Hungary against an
invasion by a Turkic tribe known as the Cumans. Then in 1226 Duke
Conrad I of Mazovia invited Hermann von Salza to move his knights
into the Baltic region to conquer and Christianize the pagans known as
the Old Prussians. Pope Honorius III had already called for a crusade
against the Prussians, but this had been unsuccessful and Duke Conrad
was thus led to bring in the Teutonic Knights, giving them a large grant
of land in Culmerland, the region around Kulm, as well as any
territory they might conquer, putting them only under the authority of
the Holy See.

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CELESTIAL REVOLUTIONARY

The Teutonic Knights slaughtered and enslaved the Prussians and
seized their lands, and by the mid-fourteenth century they had taken control of most of the northern tier of what is now Poland. The Kingdom of
Poland, much reduced in size because of the incursions of the Teutonic
Knights and other powers, began to revive under Casimir III, the Great
(r. 1333–70), the last king of the Piast dynasty, which had ruled since
the end of the tenth century.
When Casimir began his reign, the Polish economy was ruined and
the country depopulated and devastated by continual war. When he died
he left a prosperous kingdom that had doubled in size, mostly through
the addition of territory in what is today the Ukraine. He had reformed
the institutions of the kingdom, sanctioned a code of laws, built many
new castles, and, with the permission of Pope Urban V, founded a
Studium Generale in Krakow, the first institution of higher learning in
Poland. As part of his effort to repopulate the kingdom he encouraged
Jews to resettle in Poland in large numbers, protecting them as ‘people
of the king.’ As a result some 70 per cent of Ashkenazi Jews trace their
origin to Poland in the time of Casimir the Great.
Casimir had no legal sons, and so he arranged for his sister
Elisabeth, Dowager Queen of Hungary, and her son Louis, King of
Hungary, to be his successors to the Polish throne. After his death
1370, Louis was proclaimed King of Poland, though his mother
Elisabeth was the power behind the throne until her death in 1380.
When Louis died in 1382, he was succeeded by his eldest surviving
daughter, Mary, who became Queen of Hungary. But the Polish nobility were opposed to a personal union with Hungary, and they chose
Mary’s younger sister, Hedwig, who on 15 October 1384 was crowned
in Krakow as King Jadwiga of Poland, not long after her tenth birthday. (Her official title was ‘king’ rather than ‘queen’, signifying that
she was a sovereign in her own right and not just a royal consort.)
Two years later Jadwiga was betrothed to Jogaila, Grand Duke of
Lithuania, an illiterate heathen who was about 24 at the time. Jogaila
had agreed to adopt Christianity and promised to return to Poland
lands that had been ‘stolen’ by its neighbours. Jadwiga had misgivings
about the marriage, for she had heard that Jogaila was a filthy bear-like
barbarian, cruel and uncivilized, and so she sent one of her knights,
Zawisza the Red, to see if her proposed husband was really human.
Zawisza reported that Jogaila was beardless, clean and civilized, and

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OF THE

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though an unlettered heathen he seemed to have a high regard for
Christian culture. Therefore, Jadwiga went ahead with the marriage,
which was held in Krakow Cathedral on 4 March 1386, two weeks
after Jogaila was baptized. Immediately after the wedding Archbishop
Bodzanta crowned Jogaila, who became King of Poland as Wladyslaw
II Jagiello, beginning a reign that would last for 48 years. Thus started
the illustrious Jagiellonian dynasty, which reigned until 1572; its dynasts
ruling as Kings of Poland and Grand Dukes of Lithuania.
Wladyslaw and Jadwiga reigned as co-rulers, and though Jadwiga
had little real power she was very active in the political and cultural life
of Poland. She led two expeditions into Ruthenia in 1387, when she
was only thirteen, and recovered territory that had been transferred
to Hungary during her father’s reign. Three years later she personally opened negotiations with the Teutonic Knights. Jadwiga gave birth
to a daughter on 22 June 1399, but within a month both mother and
child died.
Jadwiga was renowned for her charitable works and religious foundations, which led to her canonization as a saint in 1997 by the Polish
Pope John Paul II. One of the legacies in her last will and testament
provided for the restoration of Krakow’s Studium Generale, otherwise
known as Krakow Academy, a bequest that was faithfully carried out by
King Wladyslaw, creating the institution known today as the Jagiellonian
University of Krakow.
A Polish–Lithuanian army broke the power of the Teutonic Knights
at the Battle of Tannenberg in 1410. This war ended with the First Peace
of Thorn, signed in February 1411. According to the terms of this treaty,
the Teutonic Knights held on to most of their territory through the
control of their fortified cities and towns, though their subjects grew
increasingly rebellious under the harsh rule of the Order.
During the next quarter of a century the Polish Crown fought the
Teutonic Knights in a series of three wars that devastated Prussia,
though with no territorial loss for the Order. In 1440 the gentry of
Thorn joined with other towns to form the Prussian Confederation,
which in 1454 rose up in revolt against the Teutonic Knights, beginning the Thirteen Years’ War, in which they were aided by Casimir IV
Jagiellon, King of Poland and Grand Duke of Lithuania. At the beginning of the revolt the people of Thorn stormed and captured the castle
of the Knights and killed or imprisoned its defenders. The rebellion

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CELESTIAL REVOLUTIONARY

finally ended on 19 October 1466 with the Second Peace of Thorn.
According to the terms of the treaty, the western part of the Order’s
territory along the lower Vistula came under Polish suzerainty as the
Estates of Royal Prussia, which included Thorn and Danzig, while the
wealthy see of Warmia became a separate dominion ruled by its bishop
under the Polish Crown.
The Teutonic Knights retained only the hinterland of the port
of Königsberg bounded on the southwest by Warmia. The Peace of
Thorn was reaffirmed on 8 April 1525 by the Treaty of Krakow, which
gave the Grand Master of the Teutonic Knights hereditary possession
of the Order’s territory, then known as ‘Ducal Prussia’, as a fief of the
Polish Crown.
Such was the political chequerboard of the ‘remote corner of the
earth’ where Copernicus was born and spent most of his life. His
father had moved to Thorn during the Thirteen Years’ War against
the Teutonic Knights, and he lent money to the city to help support
the soldiers of the Crown who were defending it as well as paying for
a bridge across the Vistula, later serving as magistrate and alderman.
Copernicus’ maternal grandfather, Lucas Watzenrode the Elder, had
fought against the Teutonic Knights in the Thirteen Years’ War, in which
he was wounded. He is listed in the Thorner Bürger Buch, the registry of
the citizens of Thorn, as a landowner, businessman, judge and councilman, the type of burgher who had formed the core of the resistance to
the Order of the Teutonic Knights.
Thorn was a member of the Hanseatic League, an alliance of trading
cities and their guilds that held a trade monopoly along the northern
tier of Europe from the Baltic to the North Sea. The commercial activities that led to the formation of this alliance originated in 1159 in the
northern German port city of Lübeck, ‘Queen of the Baltic’, after it was
rebuilt by Duke Henry the Lion of Saxony. Lübeck became a base for
merchants in Saxony and Westphalia to trade farther afield along the
coast from the North Sea and the Baltic and up rivers into the hinterland to cities like Thorn and Krakow, forming guilds known as Hansa,
which bound the member cities to come to one another’s aid with ships
and armed men. The formal founding of the League came in 1356 at
Lübeck, when representatives of the member cities met in the town hall
and ratified the charter of the first Hansetag, or Hanseatic Diet.

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Lübeck and other cities of the League built trading posts called kontor, founding them as far afield as the inland Russian port of Novgorod,
Bergen in Norway, and London. The London kontor, established in
1320, was west of London Bridge near Upper Thames Street on the
present site of Cannon Street station. Like Hanseatic kontors elsewhere, the trading post in London developed into a walled community with its own warehouses, weigh house, offices, houses and church.
Beside the kontors, each of the Hanseatic ports had a warehouse run
by a representative of the League, those in England located in Bristol,
Boston, Bishop’s Lynn (now King’s Lynn), Hull, Ipswich, Norwich,
Yarmouth (now Great Yarmouth) and York. Krakow, Thorn and Danzig
had Hansa representatives, the latter becoming the largest city in the
League due to its control of Polish grain exports. By the beginning of
the sixteenth century, Danzig had a population of more than 35,000,
while Krakow, the capital of the Polish Kingdom, had about 20,000
inhabitants and Thorn some 10,000.
A fifteenth-century chronicler describes Thorn in the time of
Copernicus: ‘Thorn with its beautiful buildings and its roofs of gleaming tile is so magnificent that almost no town can match it for beauty
of location and splendor of location.’ The population of the city is now
20 times greater than it was in the fifteenth century, but the old walled
town on the right bank of the Vistula is almost miraculously preserved,
with its many Gothic buildings, all in brick, laid out along the medieval network of narrow streets and around the cobbled main square,
still dominated by the Old Town Hall built in 1274 and extended in
the late sixteenth century. When viewed from the Vistula the old town
is still much the same as it appears in a lithograph done in 1684 by
Christoph Hartknoch, lacking only the sailing barges that Copernicus
would have seen in his youth, making their way along the river to and
from the docks below the city walls.
Nicolaus Copernicus was the youngest of four children, the others
being his brother Andreas and his sisters Barbara and Katherina. When
he was seven years old, the family moved from Saint Anne’s Street to a
larger house on the main square of Thorn, where the city’s weekly market was held. By that time he had started in the parochial school at the
nearby Church of St Johann, whose renown attracted students from all
over Poland. There his studies included mathematics and Latin, which

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was not only the universal academic language of Europe but was used
in the liturgy at the Church of St Johann and spoken by the merchants
of the Hanseatic League who traded in Thorn.
King Casimir IV visited Thorn in 1485, accompanied by his court,
disembarking from the royal barge beside the main gate of the city, the
entire populace there to greet him. Casimir spent six weeks in Thorn,
dining in turn at the houses of the various notables, and so the young
Nicolaus Copernicus would have met the king several times, for his
extended family included the most influential people in the city.
Niklas Koppernigk died some time between 18 July 1483 and
19 August 1485, the former date marked in the last record of his financial affairs, and the latter by a reference to him as deceased. He was
buried in the Church of St Johann, where his portrait can still be seen
on his funerary monument; a tall, slim figure with a moustache and
long black hair, shown on his knees with his hands joined in prayer. His
son Nicolaus would have been among the mourners at the funeral, left
without a father before he had even entered his teens.
Barbara Koppernigk never remarried, and she continued to live
in the house on the market square with her children until she died,
passing away some time between 1495 and 1507. Her oldest daughter,
Barbara, left the house to become a nun at the Benedictine convent in
Kulm. The youngest girl, Katherina, married a merchant from Krakow,
Bartholomaeus Gertner, who had moved to Thorn and become a city
councillor. The Gertners moved into the Koppernigk house, where
their five children were born and they continued to live until at
least 1507.
Nicolaus and his older brother Andreas were taken in hand after
their father’s death by their uncle Lucas Watzenrode, who looked after
their education. Lucas had studied at the Jagiellonian University in
Krakow in the years 1463–4, after which he went on to the University
of Cologne, where he received an MA in 1468. He then completed his
education at the University of Bologna, where in 1473 he was awarded
a doctorate in canon law.
After receiving his doctorate Lucas returned to Thorn, where he
found employment as a school teacher. At the school he became
involved with the principal’s daughter, described by a contemporary
chronicler as a ‘pious virgin’. The result of this affair was an illegitimate
son named Philipp Teschner, who later became Mayor of Braunsberg

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(Braniewo), a town in east Prussia, where he was a prominent supporter
of the Protestant Reformation.
Lucas left the school before his bastard was born, giving up teaching
and embarking on a career in the Church. The following year he was
appointed Canon of Leczyca, a town southeast of Thorn. During the
years 1477–88 he worked as a close collaborator with Sbigneus Olesnicki
the Younger, nephew of Cardinal Sbigneus Olesnicki the Elder, the most
powerful man in Poland after King Casimir IV. Lucas took up residence
with Sbigneus the Younger at Gnesen, 60 miles southwest of Thorn.
While he was there, he used his influential connections to secure new
prebends, or stipends: first the canonry of Wladyslaw in 1478, then
Warmia in 1479 and Gnesen in 1485. He was finally ordained as a priest
in 1487.
The Second Peace of Thorn in 1466 had removed Warmia from the
control of the Teutonic Knights and placed it under the sovereignty
of the Polish Crown as part of the province of Royal Prussia, although
with special privileges that gave it some degree of autonomy under its
bishop. The following year the cathedral chapter of Warmia elected
Nicolaus von Tüngen as bishop, going against the wishes of King
Casimir IV. The new bishop allied himself with the Teutonic Knights
and King Matthias Corvinus of Hungary. This led to a conflict known as
the War of the Priests, which began in 1478 when the army of the Polish
Crown invaded Warmia, putting the town of Braunsberg under siege.
The town withstood the siege, and the war ended the following year
with the Treaty of Piotrkow Trybunalski. According to the terms of the
treaty, King Casimir recognized von Tüngen as bishop and accepted
the right of the cathedral chapter of Warmia to elect future bishops,
provided that they were accepted by the Polish king and swore loyalty
to him.
On 31 January 1489 von Tüngen resigned because of ill health, and
soon afterwards the cathedral chapter elected Lucas Watzenrode as
Bishop of Warmia. The new bishop was mitred by Pope Innocent VIII,
once again against the explicit wishes of King Casimir, who had wanted
the bishopric for his son Frederic. Watzenrode prevailed, and when
Casimir died in 1492 the independence of the bishopric of Warmia was
confirmed by his son and successor John I Albert.
Bishop Lucas numbered among his close friends several humanist scholars who were leading figures in the Renaissance, most notably

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CELESTIAL REVOLUTIONARY

Jan Dlugosz, Conradus Celtes and Filippo Buonaccorsi, all three of
whom had graduated from or lectured at the Jagiellonian University
of Krakow. The young Nicolaus Copernicus would have met them as
well as other learned friends of his uncle, putting him in touch with the
humanist movement of the Renaissance at an early age.
Jan Dlugosz (1415–80), a graduate of the Jagiellonian University,
was Canon at Krakow and later Archbishop of Lemberg. He too was a
protégé of Sbigneus Olesnicki the Elder and wrote a biography of the
Cardinal. Dlugosz was tutor to the children of Casimir IV, three of whom,
John I Albert (r. 1492–1501), Alexander (r. 1501–6) and Sigismund I
(r. 1506–48), would succeed their father in turn as King of Poland. He
was sent by Casimir on diplomatic missions to the Papacy and the court
of the Holy Roman Emperor, and was involved in the King’s negotiations with the Teutonic Knights during the Thirteen Years’ War and at
the peace negotiations afterwards. Dlugosz is best known for his Annale
seu cronicae incliti Regni Poloniae (Annals or chronicles of the famous
Kingdom of Poland) and Historiae Polonicae librii XII (Polish Histories,
in 12 books). The first of these works covers events not only in Poland
but elsewhere in Europe from 965 up until the author’s death in 1480,
in which he synthesizes historical information with legends and possibly fiction.
Conradus Celtes (1459–1508) was born in Germany under his
original name Konrad Bickel, which he Latinized when he began
his higher studies, first at the University of Cologne and then at the
University of Heidelberg. After finishing university he gave humanist
lectures, first in central Europe and then in Rome, Florence, Bologna
and Venice. His first book was Ars versificandi et carminum (The art of
writing verses and poems), published in 1486. When he returned to
Germany, he was brought to the attention of Emperor Frederick II,
who named him Poet Lauraeate, after which he was given a doctoral
degree by the University of Nuremberg. After making a lecture tour
of the Holy Roman Empire, he travelled to Krakow and joined the
Jagiellonian University, lecturing on mathematics, astronomy and the
natural sciences. In Krakow he collaborated with other poets in founding a learned society based on the Roman academies, the Sodalitas
Litterarum Vistulna (Literary Society of the Vistula). Celtes founded
other branches of this society in Hungary, Austria and Germany, where
he was made a professor at the University of Heidelberg. In 1497 he

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‘THIS REMOTE CORNER

OF THE

EARTH’

was called to Vienna by Emperor Maximilian I, who appointed him
Teacher of the Art of Poetry and Conversation, with imperial privileges. This was the first time such an honour had been bestowed. In
Vienna he lectured on the works of classical Greek and Latin writers
and in 1502 founded the Collegium Poetarum, a college for poets. He
was appointed Head of the Imperial Library founded by Maximilian,
and collected numerous Greek and Roman manuscripts, his most
notable discovery being the Tabula Peutingeriana, or Peutinger Table, the
only known surviving map of the Roman Empire, with annotated itineraries for the aid of travellers. Celtes was working on the publication
of the Peutinger Table when he died of syphilis in Vienna on 4 February
1508. The disease was then known as ‘morbus gallicus’, or the ‘French
disease’, which he had apparently contracted while lecturing in Italy.
His most enduring influence was in historical studies, for he was the
first to teach the history of the known world as a whole.
Filippo Buonaccorsi (1437–96) was born in San Gimignano in
Tuscany. He took the surname Callimachus after he moved to Rome in
1462 and became a member of the Roman Academy of Julius Pomponius
Laetus. The paganist views and licentious lifestyle of the academicians
led Pope Paul II to have them all arrested in 1467, but they pleaded for
mercy and were soon released. Buonaccorsi and other members of the
Academy took part in an unsuccessful attempt to assassinate the Pope in
1468, after which he fled to Poland. When the Pope’s agents searched
the Academy, they found homosexual verses written by Buonaccorsi to
the Bishop of Segni, Lucio Fazini. The Pope’s persecution of the academicians came to a sudden end when he died of a stroke on 26 July 1471,
supposedly while being sodomized by a page boy.
When Buonaccorsi arrived in Poland he first found employment
with Gregory of Sanok, Bishop of Lemberg. Later he was hired by King
Casimir IV as tutor of the royal children, together with Jan Dlugosz. He
was named royal secretary in 1474, subsequently serving as ambassador
to the Sublime Porte in Istanbul and then acting as the King’s representative in Venice. Buonaccorsi collaborated with Conradus Celtes in
founding the Sodalitas Litterarum Vistulna in Krakow. He spent the rest
of his days lecturing at the Jagiellonian University of Krakow, as well as
writing poetry and prose in Latin. His best known works are biographies of King Wladyslaw III, Cardinal Sbigneus Olesnicki the Elder and
Bishop Gregory of Sanok, all of whom had been his patrons.

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The cathedral of the Warmia bishopric was at Frauenburg
(Frombork), a port town about 100 miles east of Danzig. Not far to the
east of Frauenburg was the smaller town of Braunsberg, where Philipp
Teschner was appointed as mayor after his father Lucas Watzenrode
became Bishop of Warmia. Lucas had always acknowledged his illegitimate son, and so it would seem that he had arranged Teschner’s
appointment as mayor.
The Bishop’s palace was at Heilsberg (Lidzbark Warminski), 140
miles northeast of Thorn, to which Lucas returned as often as he could
to visit his family and look after his nephews Andreas and Nicolaus.
Lucas had decided that the two boys would follow in his footsteps, beginning as canons in his own cathedral chapter in Frauenberg, for with his
powerful position and influential connections he could ease their way
to the top of the Catholic hierarchy in Poland, particularly in the case
of Nicolaus, for whom he seemed to have had great expectations.
When Nicolaus was 15 his uncle Lucas sent him to the cathedral
school at Wloclawek, some 30 miles up the Vistula, where he would
be prepared for his higher studies. Most of the teachers at the school
were graduates of the University of Krakow, the most notable being
Dr Nicolaus Wodka, who Latinized his name as Abstemius. Abstemius
was a specialist in gnomonics, the study of shadows cast by a gnomon,
the pointer on a sundial, and Nicolaus probably studied astronomy
with him. There is a tradition that the sundial on the south side of
Wloclawek Cathedral was constructed by Copernicus in collaboration
with Abstemius.
After Nicolaus graduated from the school at Wloclawek, he
and Andreas were sent by their uncle Lucas to his alma mater, the
Jagiellonian University in Krakow. And so, after the arrangements had
been made, Nicolaus and his brother set out from Thorn to Krakow in
the autumn of 1491, beginning a journey that would eventually bring
about an intellectual revolution and change a world view that had been
held since antiquity.

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CHAPTER 2

A New Age

The latter half of the fifteenth century was the twilight of the medieval
period and the dawn of a new era, the Renaissance of Western Europe.
In 1453, 20 years before the birth of Copernicus, the Turks captured
Constantinople, the capital of the Byzantine Empire and the Christian
continuation of the Roman Empire. Two years later the Gutenberg Bible
was printed. Nineteen years after Copernicus was born, Christopher
Columbus discovered America, opening up a New World at the beginning of a new age.
The European Renaissance was the culmination of a 1,000 years
of development that began after the collapse of Graeco-Roman civilization. The Roman Empire had been divided since ad 330, when
Constantine the Great moved his capital to the city of Byzantium on the
Bosphorus, renaming it Constantinople. The Western Empire finally
came to an end in 480 with the death of Julius Nepos, the last Emperor
of the West, who was assassinated in Dalmatia, the last remnant of his
domain. Thenceforth, the Emperor in Constantinople was sole ruler of
what remained of the Empire.
By the end of the fifth century ad the Roman Empire had been
reduced to the predominately Greek-speaking East, where Christianity
was rapidly supplanting the worship of the ancient Graeco-Roman deities. The heart of the Empire was now Asia Minor, where a Greek was
more likely to be called a Rhomaios, or Roman, rather than a Hellene,
which had come to mean a pagan, while the people of Constantinople
referred to themselves as Byzantini, or Byzantine, and were Christian.
Modern historians consider the end of the fifth century to be a watershed

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CELESTIAL REVOLUTIONARY

in the history of the Empire, which thenceforth is generally referred to
as Byzantine rather than Roman.
The peak of the Byzantine Empire came under Justinian I (r. 527–65),
who reconquered many of the lost dominions of the Empire, so that the
Mediterranean once again became a Roman sea. Justinian I also broke
the last direct link with the classical past when in 529 he issued an edict
forbidding pagans to teach. As a result the ancient Platonic Academy
in Athens was closed, ending an existence of more than nine centuries,
as its teachers went into retirement or exile.
By the end of the eighth century, after successive invasions by the
Persians, Arabs and Slavs, the Empire was reduced to little more than
Asia Minor and a few enclaves in Greece, Italy and Sicily. Athens was
utterly destroyed by the barbarian Heruli around 590, and was virtually
uninhabited for centuries afterwards, while Alexandria was taken by
the Arabs in 639, its great library having been destroyed two centuries
earlier by a mob of Christian fanatics. The great centres of the ancient
Graeco-Roman world had fallen, leaving only Constantinople as a beleaguered bastion of a Christianized remnant of classical civilization.
The Library of Alexandria had preserved the writings of all the
Greek writers from Homer onward. After its destruction, all of
the original works of Greek philosophy and science were lost, but
copies of many of them survived and eventually made their way to
Western Europe by a number of routes and through various chains of
translation.
The first Greek philosophers of nature had emerged in the sixth
century bc in the Greek colonies on the Aegean coast of Asia Minor
and its offshore islands, as well as in Magna Graecia, the Greek cities
in southern Italy and Sicily. They were known as physikoi, or physicists,
from the Greek physis, meaning ‘nature’ in its widest sense, for they were
the first who tried to explain phenomena on natural rather than supernatural grounds. Now called the Presocratics, they included Thales,
Anaximander, Anaximenes, Pythagoras, Xenophanes, Heraclitus,
Parmenides, Empedocles and Anaxagoras.
Anaxagoras, one of the last of the Presocratics, was born about
500 bc in Clazomenae, one of the Greek cities on the Aegean coast
of Asia Minor, and when he was about 20 he moved to Athens, which
emerged as the political and intellectual centre of the Hellenic world

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A NEW AGE

after the end of the Persian Wars in 479 bc, beginning the classical
period in Greek history. Anaxagoras was the first philosopher to dwell
in Athens, where he became the teacher of Pericles, who, in his famous
funeral oration in 431 bc, honoured the Athenians who fell in the first
year of the Peloponnesian War. He reminded his fellow citizens that
they were fighting to defend a free and democratic society that was
‘open to the world,’ and whose ‘love of the things of the mind’ had
made their city ‘an education to Greece.’
Pericles was referring to the famous philosophical schools of Athens,
the most renowned of which emerged in the following century: the
Academy of Plato (427–347 bc), who had been a disciple of Socrates
(469–399 bc), and the Lyceum of Aristotle (384–322 bc), who been
Plato’s pupil at the Academy.
Most of the great philosophers and scientists of the classical period
taught in Athens, the most notable exceptions being Hippocrates of
Kos (460–c.370 bc), the father of Medicine, and Democritus of Abdera
(c.470–c.404 bc), who with his teacher Leucippus formed the atomic
theory.
Plato believed that mathematics was a prerequisite for the dialectical process that would give future leaders the philosophical insight
necessary for governing a state. The mathematical study included
arithmetic, plane and solid geometry, harmonics and astronomy.
Harmonics involved a study of the physics of sound as well as an analysis
of the numerical relations supposedly developed by the Pythagoreans
in their researches on music. This led the Pythagoreans to believe that
the cosmos was designed according to harmonious principles, as is
evident not only in music but in the eternally recurring motions of
the heavenly bodies, the eternal ‘harmony of the celestial spheres.’
Astronomy was studied not only for its practical applications, but for
what it revealed of ‘the true numbers’ and ‘true motions’ behind the
apparent movements of the celestial bodies.
Plato considered that philosophers should approach the study of
nature, particularly astronomy, as an exercise in geometry. Through
this idealized geometrization of nature, relations that were as certain
as those in geometry could therefore be obtained. As Socrates remarks
in the Republic: ‘Let’s study astronomy by means of problems, as we do
geometry, and leave the things in the sky alone.’

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The main difficulty in Greek astronomy was to explain the apparent motion of the stars, the sun, the moon and the five visible planets.
These are known as the celestial bodies and they all seem to rotate
daily about a point in the heavens, namely the celestial pole, which
is caused by the axial rotation of the earth in the opposite direction.
Although the sun rises in the east and sets in the west each day, it
appears to move back from west to east by about one degree from
day to day, hence traversing the 12 signs of the zodiac in one year,
which is a phenomenon caused by the orbiting of the earth around
the sun.
The apparent path of the sun through the zodiac (i.e., the ecliptic)
makes an angle of about 23.25 degrees with the celestial equator, which
is the projection of the earth’s equator out into space. This is explainable by the fact that the earth’s axis is tilted by about 23.25 degrees with
respect to the perpendicular of the ecliptic plane, which is an inclination that causes the recurring cycle of the seasons.
The planets all trace paths near the ecliptic, which seems to go
from east to west during the night alongside the fixed stars, while from
one night to the next they move slowly back from west to east around
the zodiac. Each planet also exhibits an apparent periodic retrograde
motion, which appears as a loop when plotted on the celestial sphere.
This is owed to the fact that in orbiting the sun the earth passes the
slower outer planets and is itself passed by the swifter inner ones, in
both cases making it appear that the planet is moving backwards for a
time among the stars.
According to Simplicius (c.490–c.560), Plato posed a problem for
those studying the heavens: to demonstrate ‘on what hypotheses the
phenomena [i.e., the “appearances”, in this case the apparent retrograde motions] concerning the planets could be accounted for by uniform and ordered circular motions.’
The first solution to the problem was provided by Eudoxus of Cnidus
(c.400–c.347 bc), a younger contemporary of Plato at the Academy.
Eudoxus was the greatest mathematician of the classical period, credited with some of the theorems that would later appear in the works
of Euclid and Archimedes. He was also the leading astronomer of his
era, and had made careful observations of the celestial bodies from
his observatory at Cnidus, on the southwestern coast of Asia Minor.
Eudoxus suggested that the path of the five planets was the result of

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the uniform motion of four connected spheres, all of which had the
earth as their centre, but with their axes inclined to one another and
rotating at different speeds. The planet is attached to the equator of
the innermost sphere, and the outermost sphere moves with the fixed
stars. The motions of the sun and the moon were accounted for by
three spheres each, while a single sphere sufficed for the daily rotation of the fixed stars, making a total of 27 spheres for the cosmos.
Eudoxus’ model, known as the theory of homocentric spheres, was
elaborated upon by Callipus of Cyzicus (fl. 370 bc), who added two
more spheres for the sun and moon and one more for Mercury, Venus
and Mars, to make a total of 34 spheres. The theory of homocentric
spheres was subsequently adopted by Aristotle as the physical model
for his geocentric cosmos, using 55 planetary spheres plus another for
the fixed stars.
Aristotle’s writings are encyclopaedic in scope, including works on
logic, metaphysics, rhetoric, theology, politics, economics, literature,
ethics, psychology, physics, mechanics, astronomy, meteorology, cosmology, biology, botany, natural history and zoology. The main outlines
of Aristotle’s theory of matter and his cosmology derive from earlier
Greek thought, which distinguished between the imperfect and transitory terrestrial world below the sphere of the moon and the perfect
and eternal celestial region above. He took from Thales, Anaximander
and Anaximenes the notion that there was one fundamental substance
in nature, and reconciled this with Empedocles’ concept of the four
terrestrial elements – earth, water, air and fire – to which he added the
aether of Anaxagoras, the quintessential element, as the basic substance
of the celestial region.
According to Aristotle, the fundamental terrestrial substance, which
he called prostyle, is completely undifferentiated. When this matter takes
on various qualities it becomes one of the four terrestrial elements, and
through further developments it takes on the form of the things seen in
the world. Aristotle would describe this as matter taking on form. Thus,
matter is the raw material; form is the collection of all the qualities that
give an object its distinctive character. These two aspects of existence –
matter and form – are inseparable, and can only exist in conjunction
with one another.
Aristotle’s cosmology arranged the four elements in order of density, with the immobile spherical earth at the centre surrounded by

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Figure 2 The apparent motion of the Sun through the constellations Aries and
Taurus (above); the apparent motion of Mars through the constellations Aries
and Taurus (below).

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A NEW AGE

concentric shells of water (the ocean), air (the atmosphere) and fire,
the latter including not only flames but extraterrestrial phenomena
such as lightning, rainbows and comets. The natural motion of the
four terrestrial elements moves towards their natural place, so that
if earth is displaced upward in air and released, it will fall straight
down, whereas air in water will rise, and so does fire in air. This linear
motion of the terrestrial elements is temporary since it ceases when
they reach their natural place. Aristotle’s theory of motion argues
that heavier objects fall faster than those that are light, and Aristotle
also argued against the possibility of void. These two theories that
we know are erroneous will dominate physics until the seventeenth
century.
According to Aristotle, the celestial region begins at the moon,
beyond which are the sun, the five planets and the fixed stars, all
embedded in crystalline spheres rotating around the immobile earth.
The celestial bodies are made of aether, whose natural motion is circular
at constant velocity, so that the motions of the celestial bodies, unlike
those of the terrestrial region, are unchanging and eternal.
Heraclides Ponticus (c.390–c.339 bc), named this way because he
was a native of Heraclea on the Pontus (the Black Sea), was a contemporary of Aristotle, and had also studied at the Academy under Plato.
His cosmology differed from that of Plato and Aristotle in at least two
fundamental points, which may be due to the fact that after leaving
the Academy he seems to have studied with the Pythagoreans. The
first point of difference concerned the extent of the cosmos, which
Heraclides thought to be infinite rather than finite. A second difference related to the apparent circling of the stars around the celestial
pole, which, according to Heraclides, was actually due to the rotation
of the earth on its axis in the opposite sense. Simplicius, in his commentary on Aristotle, writes that ‘Heraclides supposed that earth is in
the center and rotates while the heaven is at rest, and he thought by this
supposition to save [i.e., account for] the phenomena.’
Aristotle’s successor as director of the Lyceum was his son-in-law
Theophrastus (c.371–287 bc), to whom he gave his enormous library,
including copies of his complete works. Theophrastus headed the
Lyceum for 37 years, during which time he reorganized and enlarged
it, making him regarded as the second founder of the Lyceum.

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More than 200 works, which are now mostly lost, are attributed
to Theophrastus, whose interests was as encyclopedic as that of
Aristotle. Theophrastus is known as the father of Botany thanks to
his two extant works: History of Plants and Causes of Plants. His treatise
On Stones marks the beginning of geology and mineralogy. His work
on human behaviour, entitled Characters, is a witty description of the
types of people living in Athens during his time, all of whom still seem
to be represented in the modern city.
Two other schools of philosophy were founded in Athens late
in the fourth century bc. These were not formal institutions like
the Academy and the Lyceum, but more loosely organized groups
gathered to discuss philosophy. One of the schools, known as the
Garden, was founded by Epicurus of Samos (341–270 bc) and
the other, the Porch, was established by Zeno of Citium (c.335–
263 bc). The name of the first school came from the fact that
Epicurus lectured in the garden of his house, while the second was
named for the Stoa Poikile, or Painted Porch, in the Agora, the
meeting place of Zeno and his disciples, the Stoics. Both Epicurus
and Zeno created comprehensive philosophical systems that were
divided into three parts – ethics, physics and logic – in which the
last two were subordinate to the first, whose goal was to secure
happiness.
The physics of Epicurus was based on the atomic theory, to which
he added the new concept that an atom moving through the void
could at any instant ‘swerve’ from its path. This eliminated the
absolute determinism that had made the original atomic theory
of Leucippus and Democritus unacceptable to those who, like the
Epicureans, believed in free will. Zeno and his followers rejected the
atom and the void, for they looked at nature as a continuum in all
of its aspects – space, time and matter – as well as in the propagation
and sequence of physical phenomena. These two opposing schools
of thought about the nature of the cosmos – the Epicurean atoms in
a void versus the continuum of the Stoics – have competed with one
another from antiquity to the present, for they seem to represent
antithetical ways of looking at physical reality.
After the death of Alexander the Great in 323 bc, the beginning of the Hellenistic period, the intellectual centre of the Greek

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A NEW AGE

world shifted from Athens to Alexandria, the new city that he had
founded on the Canopic branch of the Nile. Alexandria became the
capital of a powerful kingdom ruled by Ptolemy I (r. 305–280 bc),
founder of the Ptolemaic dynasty that ruled Egypt for nearly three
centuries.
The emergence of Alexandria as a cultural centre was largely
due to the establishment of a school of higher studies known as the
Museum, called thusly because it was dedicated to the Muses. The
Museum and its famous Library were founded by Ptolemy I and
further developed by his son and successor Ptolemy II (r. 283–225
bc). By law the Library was required to obtain a copy of every work
written in the Greek world, and by the time of Ptolemy III (r. 247–
221 bc) it was reputed to have a collection of more than half a
million parchment rolls, including everything written from Homer
onward.
The first scientist to head the Library was Eratosthenes of Cyrene
(c.275–c.195 bc), and to draw a map of the known world on a system of
meridians of longitude and parallels of latitude, which, together with
observations with a gnomon, allowed him to make an accurate estimation of the earth’s circumference.
Eratosthenes was a friend of Archimedes (c.287–212 bc), who dedicated to him the famous treatise On Method. Archimedes, who was from
Syracuse in Sicily, probably studied at Alexandria under the pupils of
Euclid (fl. c.295 bc), whose great work on geometry, the Elements, he
quoted from extensively.
One of Archimedes’ works, The Sand-Reckoner, mentions a revolutionary astronomical theory proposed by his older contemporary
Aristarchus of Samos (c.310–287 bc), writing that
Aristarchus of Samos has, however, enunciated certain hypotheses in
which it results from the premises that the universe is much greater
than that just mentioned. As a matter of fact, he supposes that the fixed
stars and the sun do not move, but that the earth revolves in the circumference of a circle about the sun, which lies in the middle of the orbit,
and that the sphere of the fixed stars, situated about the same center
as the sun, is so great that the circle in which the earth is supposed to
revolve has the same ratio to the distance of the fixed stars as the center
of the sphere to its surface.

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The last sentence is of particular significance, for it explains why there
is no stellar parallax, or apparent displacement of the stars, when the
earth moves in orbit around the sun in the heliocentric theory of
Aristarchus. Even the nearest stars are so far away, compared to the
radius of the earth’s orbit around the sun, that their parallax is far too
small to be detected by the naked eye. This effect was not observed
until the mid-nineteenth century, when telescopes of sufficient resolving power had been developed.
The treatise in which Aristarchus presents his heliocentric theory
has not survived, undoubtedly because the idea conflicted with the
accepted belief that the earth was the stationary centre of the cosmos.
He also seems to have believed that the earth was not only orbiting
around the sun but also rotating on its own axis. Cleanthes of Assos,
his contemporary, is quoted by Plutarch as holding that Aristarchus
should be charged with impiety ‘on the ground that he was disturbing
the hearth of the universe because he sought to save [the] phenomena by supposing that the heaven is at rest while the earth is revolving along the ecliptic and at the same time is rotating about its own
axis.’
The only work of Aristarchus that has survived is his treatise On the
sizes and distances of the Sun and the Moon. Here the stellar and lunar sizes
and distances were calculated from geometrical demonstrations based
on three astronomical observations, together with an estimation of the
earth’s diameter. The results of these measurements led Aristarchus
to conclude that the sun is about 19 times farther from the earth than
the moon, and that the sun is approximately 6¾ times as large and
the moon about 1/3 as large as the earth. All of his values are grossly
underestimated, because of the crudeness of his observations, but his
geometrical methods were sound. His finding that the sun is larger
than the earth may have been what led him to propose his heliocentric
theory.
The other Hellenistic mathematician comparable to Euclid and
Archimedes is Apollonius of Perge, who flourished in Alexandria during the reigns of Ptolemy III and Ptolemy IV (r. 221–203 bc), as well
as in Pergamum during the reign of Attalos I (r. 241–197 bc). His only
surviving work is his treatise On Conics, the first comprehensive and
systematic analysis of the three types of conic sections: the ellipse (of
which the circle is a special case), parabola and hyperbola.

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Apollonius is also credited with formulating mathematical theories to explain the apparent retrograde motion of the planets. One
of his theories has the planet moving round the circumference of a
circle, known as the epicycle, whose centre itself moves round the
circumference of another circle, called the deferent, centred at the
earth. Another has the planet moving round the circumference of an
eccentric circle, whose centre does not coincide with the earth. He
also showed that the epicycle and eccentric circle theories are equivalent, so that either model can be used to describe retrograde planetary
motion.
Aside from the great theoreticians of the Hellenistic era, there were
also three gifted inventors. The first of these was Ctesibus of Alexandria
(fl. c.270 bc), whose written works have been lost, but whose ideas and
inventions have been preserved in the writings of his successor, Philo
of Byzantium (fl. 250 bc) and Hero of Alexandria (fl. ad 62). Hero is
famous for his steam engine, one of the thaumata, or ‘miracle-working’
devices described in his treatises On Automata and Pneumatic. The first
chapters of the latter work, which derive largely from Philo, describe
experiments demonstrating that it is possible to produce a partial
volume, contrary to Aristotelian doctrine. He also wrote a treatise on
the reflection of light, the Catoptrica, which would play an important
part in the development of early European studies of optics.
Hipparchus of Nicaea (fl. 147–127 bc) was the greatest observational astronomer of antiquity, whose observations were later used
by Claudius Ptolemaeus (c. ad 100–c.170). All of his writings have
been lost except for his first work, a commentary on the Phainomena
of Aratus of Soli (c.310–c.240 bc), a Greek poem describing the
constellations. Phainomena served to popularize the names of stars
and constellations, which have been perpetuated in the modern
world. It contains a catalogue of some 850 stars, for each of which
Hipparchus gives the celestial coordinates, including those of a
‘nova’ or ‘new star,’ which suddenly appeared in 134 bc in the constellation Scorpio. He also estimated the brightness of the stars,
assigning to each of them a ‘magnitude,’ which equalled one for
the brightest stars and six for the faintest, a system still used in
modern astronomy.
Hipparchus is famous for his discovery of the precession of the
equinoxes, which, in brief terms, is the slow continuous shift in the

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orientation of the earth’s rotational axis, whose direction remains perpendicular to the ecliptic. Hipparchus discovered this phenomenon
by comparing his star catalogue with observations made 128 years earlier by the astronomer Timocharis, which led him to conclude that the
annual precession moved at a rate of 45.2 arc seconds.
Hipparchus is also celebrated as a mathematician particularly for his
development of spherical trigonometry, which he applied to problems
in astronomy.
A younger contemporary of Hipparchus, the Greek astronomer and
mathematician Theodosius of Bithynia (c.160-c.100 bc) is known for his
Sphaerica, a treatise on the application of spherical geometry to astronomy, which was translated into Arabic and later into Latin. His work
remained in use up until the seventeenth century.
Ancient Greek mathematical astronomy reached with the work of
Claudius Ptolemaeus, known more simply as Ptolemy, who flourished
in the mid-second century ad in Alexandria. The most influential of his
writings is Mathematical Synthesis, a comprehensive work on theoretical
astronomy better known by its Arabic name, the Almagest.
The topics in the Almagest are treated in logical order through the
13 books. Book I begins with a general discussion of astronomy, including Ptolemy’s view that the earth is stationary ‘in the middle of the
heavens.’ The rest of Book I and all of Book II are devoted principally
to the development of the spherical trigonometry necessary for the
whole work. Book III deals with the motion of the sun and Book IV
with lunar motion, which is continued at a more advanced level in
Book V along with solar and lunar parallax. Book VI is on eclipses;
Books VII and VIII are on the fixed stars; and Books IX through XIII
are on the planets.
Ptolemy’s trigonometry and catalogue of stars are based on the work
of Hipparchus, and his theory of epicycles and eccentrics is derived
from Apollonius. The principal modification made by Ptolemy is that
the centre of the epicycle moves uniformly with respect to a point
called the equant, which is displaced from the centre of the deferent circle, a device that was to be the subject of controversy in later
times.
The extant astronomical writings of Ptolemy also include the Handy
Tables, Planetary Hypotheses, Phases of the Fixed Stars, Analemma and
Planisphaerium; as well as a work on astrology called the Tetrabiblos;and

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Figure 3 Epicycle model for explaining the apparent retrograde motion of the
planets (above); Ptolemy’s equant model (below).

treatises entitled Optics, Geography and Harmonica, the latter devoted to
musical theory.
Galen (130–c.204), known in medieval Europe as the ‘Prince of
Physicians’, was born in Pergamum in Asia Minor. He served his medical apprenticeship at the healing temple of Asclepios at Pergamum,
where his work treating wounded gladiators gave him an unrivalled
knowledge of human anatomy, physiology and neurology. He then travelled extensively and studied in many cities, including Smyrna, Corinth
and Alexandria among others. In 161 he settled in Rome, where he
was to spend most of the rest of his life serving as physician to three

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emperors. Galen’s writings, translated into Arabic and Latin, served as
the foundation of human anatomy and physiology up until the seventeenth century.
Another figure who came to study in Alexandria was Dioscorides
Pedanius (fl. 50–70), from Anazarbus in southeastern Asia Minor,
who later became a physician in the Roman army during the reigns
of Claudius (r. 41–54) and Nero (r. 41–68). Dioscorides is regarded as
the founder of pharmacology, renowned for his De Materia Medica, a
systematic description of some 600 medicinal plants and nearly 1,000
drugs.
The last great mathematician of antiquity was Diophantus of
Alexandria (fl. c.ad 250), who did for algebra and number theory what
Euclid had done for geometry. The work of Diophantus is still a part
of modern mathematics, studied under the heading of Diophantine
Analysis.
Theon of Alexandria (c.335–c.405), who flourished in the second
half of the fourth century, is noted in the Museum and Library, particularly for a passage in his commentary on a work by Ptolemy, where he
states that ‘certain ancient astrologers’ believed that the points of the
spring and autumn equinox oscillate back and forth along the ecliptic, moving through an angle of 8 degrees over a period of 640 years.
This erroneous notion was revived in the so-called trepidation theory
of Arab astronomers, and it survived in various forms up into the sixteenth century, when it was discussed by Copernicus.
After Justinian closed the Platonic Academy in Athens in 529,
seven of its scholars went into exile, and in 531 they were given refuge
by the Persian king Chosroes I, who appointed them to the faculty
of the medical school at Jundishapur. Among them were Simplicius
of Cilicia, Damascius and Isidorus of Miletus, the latter two having
been the last directors of the Platonic Academy in Athens. The following year they were all allowed to return from exile, with Isidorus
taking up residence in Constantinople and the others going back to
Athens.
Justinian appointed Isidorus and his colleague Anthemius of Tralles
to build the great church of Haghia Sophia in Constantinople, which
was completed in 537 and survives virtually intact today, the supreme
masterpiece of Byzantine architecture. Isidorus and Anthemius were

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the last mathematical physicists of antiquity, both of them authors of
commentaries that are important links in the survival of Archimedes’
writings.
Simplicius is known for his commentaries on Aristotle, whose
ideas he defended against the criticism of his contemporary John
Philoponus, particularly on the question of why a projectile, such as an
arrow, continues moving after it is propelled. One of the last directors
of the Platonic school in Alexandria, Philoponus (490–570) rejected
the Aristotelian projectile theory presented by Simplicius, which was
that the air displaced by the arrow flows back to push it from behind,
a spurious effect called antiperistasis. Instead, Philoponus maintained
that the arrow, when fired, receives an ‘incorporeal motive force’, an
important concept that was revived in medieval Europe as the ‘impetus theory’. Thus in the last days of antiquity an important debate
took place on a fundamental scientific concept, just as the last light of
classical Graeco-Roman civilization was being occulted at the onset of
the Dark Ages.
Most of the Greek philosophical and scientific works that survived
made their way through the Hellenized Syriac-speaking Christians of
Mesopotamia to the Islamic world after 762, when the Abbasid Caliph
al-Mansur founded Baghdad as his new capital. Baghdad emerged as
a great cultural centre under al-Mansur (r. 754–75) and three generations of his successors, particularly al-Mahdi (r. 775–85), Harun
al-Rashid (r. 786–809) and al-Ma’mun (r. 813–33). According to the
historian al-Mas’udi (d. 956), al-Mansur ‘was the first caliph to have
books translated from foreign languages into Arabic,’ including
‘books by Aristotle on logic and other subjects, and other ancient
books from classical Greek, Byzantine Greek, Pahlavi, Neopersian,
and Syriac.’ These translations were done at the famous Bayt al-Hikma,
or House of Wisdom, a library established in Baghdad early in the
Abbasid period.
The program of translation continued until the mid-eleventh
century, both in the East and in Muslim Spain. By that time most of
the important works of Greek science and philosophy were available
in Arabic translations, along with commentaries on these works and
the original treatises by Islamic scientists that had been produced in
the interim. Thus, through their contact with surrounding cultures,

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scholars writing in Arabic were in a position to take the lead in science
and philosophy, absorbing what they had learned from the Greeks and
adding to it, hence beginning an Islamic renaissance, whose fruits were
eventually passed on to Western Europe.
Some fragments of classical learning were also preserved in Latin
Europe. These included writers of the Roman era, most notably
Lucretius (c.94–50 bc), who wrote a superb didactic poem entitled De
Rerum Natura (On the Nature of Things), based on the atomic theory
of Democritus. De Rerum Natura became popular in medieval Europe,
eventually leading to the revival of the atomic theory in the seventeenth
century.
During the early medieval period, the attitude of Christian scholars
was that the study of science was not necessary, for in order to save one’s
soul it is enough to believe in God, as St Augustine of Hippo (354–
430) wrote in his Enchiridion: ‘It is enough for Christians to believe that
the only cause of created things, whether heavenly or earthly, whether
visible or invisible, is the goodness of the Creator, the one true God,
and that nothing exists but Himself that does not derive its existence
from Him.’
The most important figure in the transmission of ancient Greek
knowledge to early medieval Europe is Anicius Manlius Severinus
Boethius (c.480–525). Boethius, who was from an aristocratic Roman
family, held high office under the Ostrogoth king Theodoric, who had
him imprisoned and executed. His best known work is his Consolation
of Philosophy, written while he was in prison before his execution. The
other works of Boethius fall into two categories: his translations from
Greek into Latin of Aristotle’s logical works, and his own writings on
logic, theology, music, geometry and arithmetic. His writings were
influential in the transmission to medieval Europe of the basic parts of
Aristotle’s logic and of elementary arithmetic.
The grand plan envisioned by Boethius was to transmit, in Latin,
the intellectual achievements of the ancient Greeks. As he wrote in
one of his commentaries: ‘I shall transmit and comment upon as many
works by Aristotle and Plato as I can get hold of, and I will try to show
that their philosophies agree.’ He also noted, in the introduction to
his Arithmetic, a handbook for each of the disciplines of the quadrivium:
arithmetic, geometry, astronomy and musical theory. The extant writings of Boethius also include translations and/or commentaries on at

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least five logical works by Aristotle, as well as translations of Euclid’s
Elements.
The revival of learning in Western Europe began in an Irish monastery
in the sixth century. The first Irish monasteries were probably founded
by priests from Britain and Gaul fleeing the Anglo-Saxon and Germanic
invasions of the fifth and sixth centuries, as well as a few from the Greek
world who came to both Ireland and Britain, bringing with them their
language and certain texts that were not found elsewhere in Europe.
St Columba (521–97) founded monasteries in Ireland, at Derry and
Durrow, and then in 561 he went off into exile in Scotland along with
12 companions. He was granted land off the west coast of Scotland on
the island of Iona, which became the centre of his evangelizing mission
to the Picts.
St Benedict Biscop (c.628–90) was the founding abbot of the monasteries at Wearmouth and Jarrow on Tyne in Northumbria, making
five trips to Rome to stock their libraries, which became famous
throughout medieval Europe. On his third trip to Rome Benedict
returned with Theodore of Tarsus (602–90), a Greek from Asia
Minor who had studied in Antioch and Constantinople before joining a monastery in Rome, where in 668 Pope Vitalianus (r. 757–68)
appointed him as Archbishop of Canterbury. Benedict also brought
back Hadrian the African, a Greek-speaking Berber monk from North
Africa who had twice turned down appointments to the archbishopric
of Canterbury.
Theodore and Hadrian founded a monastic school at Canterbury
that began what has been called the golden age of Anglo-Saxon scholarship. Theodore and Hadrian taught Greek and Latin as well as
arithmetic and physical science. Students from the Wearmouth and
Jarrow went on to become abbots of Benedictine monasteries elsewhere in England, spreading the knowledge of they had gained in
Canterbury.
The Venerable Bede (674–735), writing in 731, says that at the age
of seven he was entrusted to the care of Benedict Biscop at Wearmouth,
where he began the studies that he would continue for the rest of his
life there and at Yarrow. Bede’s best known work is the Historia ecclestiastica gentis Anglorus (The Ecclesiastical History of the English People),
completed in about 731. Bede wrote several opera didascalica, textbooks
designed for vocational courses in monastic schools such as notae (scribal

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work), grammar (literary science) and computus (the art and science of
telling time). His scientific writings include two treatises on astronomical timekeeping and a book called De Rerum Natura. The latter work
presents his views on cosmology, which was based on the Aristotelian
model in which the terrestrial region of the central earth is surrounded
by the nested spheres of the celestial region.
Bede’s tradition of learning was perpetuated by his student and
disciple Egbert, Archbishop of York. The cathedral school that Egbert
founded at York rivalled the famous monastic schools at Wearmouth
and Jarrow, renowned not only in religious studies but in the seven
liberal arts of the trivium and quadrivium as well as in literature and
science, its library reputed to be the finest in Britain.
The most distinguished student at the York school in its early days
was Alcuin of York (c.735–804), who had been enrolled there as a young
boy by Egbert. On his way home from a mission to Rome in 781 Alcuin
met Charlemagne, ‘King of the Franks’, who had in 768 inherited a
realm now known as the Carolingian Empire, which including portions of what is now Germany and most of present-day France, Belgium
and Holland, to which he eventually added more German territory, all
of Switzerland, part of Austria, and half of Italy. Charlemagne asked
Alcuin to join his court at Aachen as his principal advisor on ecclesiastical and educational matters.
Alcuin arrived in Aachen in 782 and was appointed Head of the
Palace School, which had been founded by the earlier Merovingian
kings to educate the royal children, principally in courtly ways and
manners. Charlemagne wanted to broaden the education of his children and other members of his court to include the study of religion and the seven liberal arts. His students included Charlemagne
himself as well as his sons Pepin and Louis, as well as young men
sent to the court for their education along with clerics at the palace
chapel.
Alcuin drew up a standardized curriculum and wrote textbooks
and manuals for the Palace School, establishing the ancient trivium
and quadrivium as the basis for education. He also introduced the various disciplines of the computus, including sufficient mathematics and
astronomy for understanding the calendar, particularly the dating of
Easter.

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Charlemagne issued an edict establishing monastic and cathedral
schools throughout his realm. Students at the monastic and cathedral
schools included not only clerics but also externs, or laymen, which
led to an increase in Latin literacy among Charlemagne’s subjects.
Alcuin supervised the organization of these schools as well as their
curricula and textbooks, which were based on the seven liberal arts.
Many of his pupils at the Palace School went on to become bishops
and abbots, significantly raising the educational level of the clergy,
particularly those who directed and taught at the monastic and cathedral schools.
The Carolingian educational reforms produced the first major
figure in what would become the new European science. This was
Gerbert d’Aurillac (c.945–1003), who became Pope Sylvester II (r.
999–1003). Gerbert was born in humble circumstances in or near
Aurillac, in southwestern France, and received his early education at
the local Benedictine monastery of St Géraud. His precocious brilliance brought him to the attention of Count Borel of Barcelona who
took him from the monastery in 967 as his protégé. He continued his
studies in Barcelona under the aegis of Borel, who put him under the
tutelage of Atto, Bishop of Vic. Gerbert concentrated on mathematics,
probably studying the works of late Roman writers such as Boethius
and Cassiodorus, which would have included some arithmetic, geometry (though without proofs) and astronomy, as well as Pythagorean
number theory. He would also have learned the mensuration rules of
ancient Roman surveyors.
While Gerbert was in Barcelona he seems to have come in contact
with Islamic manuscripts, though probably only in Latin translation.
Gerbert is credited with a treatise on the astrolabe entitled De astrolabia, as well as the first part of a work entitled De utilitatibus astrolabi,
both of which show Arabic influence. The astrolabe, an astronomical instrument and calculating device, was invented by the ancient
Greeks, probably by Hipparchus, and was widely used by Islamic
astronomers.
Gerbert’s attested writings include works on mathematics, one of which
is a treatise on the abacus, a calculating device that is believed to have
come to the Islamic world from China. He also seems to have used the
Hindu-Arabic numbers which were subsequently adapted and became the

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basis for the ones used today. Thus it would appear that Gerbert was one
of the first European scholars to make use of the Graeco-Islamic scientific
heritage in developing the new science that was beginning to emerge in
Western Europe.
Gerbert came to the attention of Otto I (r. 962–73), the Holy Roman
Emperor, who was then residing in Rome. Otto arranged for Gerbert’s
assignment to Adalboro, Archbishop of Rheims, who was appointed
Master of the Cathedral School there, which he reorganized with
such success that students flocked to it from all parts of the Empire.
Gerbert’s students are known to have gone on to teach at eight other
cathedral schools in northern Europe, where they emphasized the
mathematics and astronomy he had learned from Islamic sources in
Spain.
The development of European science began to accelerate when the
heritage of Graeco-Islamic learning became available to Latin scholars
in the West, beginning with Gerbert d’Aurillac.
Adelard of Bath (fl. 1116–42) was the leading figure in the
European acquisition of Arabic science. In the introduction to his
Questiones Naturales, addressed to his nephew, Adelard writes of his
‘long period of study abroad,’ first in France, where he studied at
Tours and taught at Laon. He then went on to Salerno, Sicily, Tarsus,
Antioch and probably also to Spain, spending a total of seven years
abroad.
Adelard may have learned Arabic in Spain, for his translation of
the Astronomical Tables of the Arabic scholar al-Khwarizmi (fl. c.828)
was from the revised version of the Andalusian astronomer Maslama
al-Majriti (d. 1034). The Tables, comprising 37 introductory chapters
and 116 listings of celestial data, provided Christian Europe with its
first knowledge of Graeco-Arabic-Indian astronomy and mathematics,
including the first tables of the trigonometric sine function to appear
in Latin. He also translated the Introduction to Astrology of Abu Ma’shar
(787–886).
Adelard may also have been the author of the first Latin translation
of another work by al-Khwarizmi, De Numero Indorum (Concerning the
Hindu Art of Reckoning). This work, probably based on an Arabic
translation of works by the Indian mathematician Brahmagupta
(fl. 628), describes the Hindu numerals that eventually became the

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digits used in the modern Western world. The new notation came to
be known as that of al-Khwarizmi, corrupted to ‘algorism’ or ‘algorithm’, which now means a procedure for solving a mathematical
problem in a finite number of steps that often involves repetition of
an operation.
Adelard was probably also the first to give a full Latin translation
of Euclid’s Elements, in three versions. The second of these became
very popular, beginning the process that led to Euclid’s domination of
medieval European mathematics.
Adelard says that his Questiones Naturalis was written to explain ‘something new from my Arab studies.’ The Questiones are 76 in number, 1–6
dealing with plants, 7–14 with birds, 15–16 with mankind in general,
17–32 with psychology, 33–47 with the human body, and 48–76 with
meteorology and astronomy. Throughout he looks for natural rather
than supernatural causes of phenomena, a practice that would be followed by later European writers. The Questiones Naturalis remained
popular throughout the rest of the Middle Ages, with three editions
appearing before 1500, as well as a Hebrew version. Adelard also wrote
works ranging from trigonometry to astrology and from Platonic philosophy to falconry. His last work was a treatise on the astrolabe, in
which once more he explained ‘the opinions of the Arabs,’ this time
concerning astronomy.
Toledo became a centre for translation from the Arabic after its
recapture from the Moors in 1085 by Alfonso VI, King of Castile and
León, the first major triumph of the reconquista, the Christian reconquest of al-Andalus. Gerard of Cremona (1114–87), the most prolific of
all the Latin translators from the Arabic, first came to Toledo no later
than 1144, and ‘there, seeing the abundance of books in Arabic on
every subject [. . .] he learned the Arabic language, in order to be able
to translate.’
Gerard’s translations include Arabic versions of writings by Aristotle,
Euclid, Archimedes, Ptolemy and Galen, as well as works by al-Kindi
(c.801–66), al-Khwarizmi, al-Razi (c.854–c.930), Ibn Sina (Avicenna)
(c.980–1037), Ibn al-Haytham (Alhazen) (c.965–c.1041), Thabit ibn
Qurra (c.836–901), al-Farghani (d. after 861), al-Farabi (870–950),
Qusta ibn Luqa (d. 912), Jabir ibn Hayyan (c.721–c.815), al-Zarqali (d.
1100), Jabir ibn Aflah (c.1120), Masha’allah (c.762–c.809), the Banu

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Musa (d. second half of the ninth century) and Abu Ma’shar (d. 886).
The subjects covered in these translations include 21 works on medicine; 17 on geometry, mathematics, optics, weights and dynamics; 14
on philosophy and logic; 12 on astronomy and astrology; and 7 on
alchemy, divination and geomancy, or predicting the future from geographic features.
More of Arabic science was transmitted to Western Europe through
Gerard than from any other source. His translations had considerable
influence upon the development of European science, particularly
in medicine, where students in the Latin West took advantage of the
more advanced state of medical studies in medieval Islam. His translations in astronomy, physics and mathematics were also very influential, since they represented a scientific approach to the study of nature
rather than the philosophical and theological attitude that had been
prevalent in the Latin West. His translation of Ptolemy’s Almagest was
particularly important, for as a modern historian of science has noted,
through this work ‘the fullness of Greek astronomy reached western
Europe.’
The Dominican monk William of Moerbeke (c.1220–35 – before
1286), in Belgium, was the most prolific of all medieval translators
from Greek into Latin. Moerbeke claims that he undertook this
translation task ‘in order to provide Latin scholars with new material
for study.’ Moerbeke’s translations included the writings of Aristotle,
Archimedes, Hero of Alexandria, Ptolemy and Galen. His translations contributed to a better knowledge of the actual Greek texts
of several works, and in some rare cases these constituted the only
remaining evidence of Greek texts long lost, such as that of Hero’s
Catoptrica.
By the end of the twelfth century European science was on the
rise, stimulated by the enormous influx of Graeco-Islamic works translated into Latin from Arabic as well as other works translated directly
from Greek. By the first quarter of the following century virtually all
of the scientific works of Aristotle had been translated into Latin,
from Greek as well as Arabic, along with the Aristotelian commentaries of Ibn Rushd (Averroës) (1126–98). The translations included
other works by both Greek and Islamic scientists on optics, geometry, astronomy, astrology, zoology, botany, medicine, pharmacology,
psychology and mechanics. This body of knowledge became part of

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the curriculum at the first universities that began to emerge in the
late medieval era. During the following centuries European scholars
would absorb Graeco-Islamic learning and begin to make advances
of their own, developing the new science that would emerge with the
dawn of the new age.

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CHAPTER 3

The Jagiellonian
University of
Krakow

When Nicolaus and Andreas arrived in Krakow in the autumn of 1491,
the city had a population of some 20,000, a fortieth of what it is today.
The city had been the capital of Poland since the reign of Casimir I,
the Restorer (r. c.1034–58), the fourth ruler of the Piast dynasty that
had been founded by Mieszko I (r. 960–92). It was devastated during
the Mongol invasions that swept across Eastern Europe in 1241, 1259
and 1287 and almost destroyed the Polish kingdom, which was reunified under Wladyslaw Lokietek (r. 1306/20–33), the first king to be
crowned in Krakow.
The burghers in Krakow at the time were predominately German
and German-speaking. Indigenous Poles were forbidden to live in the
city since princes and landlords feared the loss of manpower from their
estates, though many peasants managed to settle anyway.
Krakow began to rise to prominence after the university was founded
in 1364, and as capital of the Polish kingdom and member of the
Hanseatic League the city began to attract craftsmen, businesses and
guilds, thus becoming a centre of learning and the arts. The city also
counted a large Jewish minority who were ordered out of the centre
of Krakow in 1495 and resettled in the Kazimierz quarter, which was
divided into Christian and Jewish sections.

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The founding of the University of Krakow, along with those elsewhere in Europe, was stimulated by the assimilation of Graeco-Islamic
science, first in translation from Arabic to Latin and later from the
original Greek.
The earliest institution of higher learning was the university
of Bologna, founded in 1088, followed in turn by Paris (c.1150),
Oxford (1167), Salerno (1173, a refounding of the medical school),
Palenzia (c.1178), Reggio (1188), Vicenza (1204), Cambridge (1209),
Salamanca (1218) and Padua (1222), to name only the first ten. Another
ten were founded in the remaining years of the thirteenth century. In
the fourteenth century 25 more were founded with another 35 in the
fifteenth, so that by 1500 there were 80 universities in Europe. This is an
evidence of the tremendous intellectual revival that had taken place in
the West, and that started with the initial acquisition of Graeco-Islamic
learning in the twelfth century.
Bologna became the archetype for later universities in Southern
Europe, Paris and Oxford for those in the northern part of the continent. Bologna was renowned for the study of law and medicine, Paris
for logic and theology, and Oxford for philosophy and natural science. Training in medicine was based primarily on the teachings of
Hippocrates and Galen, while studies in logic, philosophy and science
were based on the works of Aristotle and commentaries upon them.
Although Aristotle’s works formed the basis for most non-medical
studies at the new universities, some of his ideas in natural philosophy, particularly as interpreted in commentaries by Averroës, were
strongly opposed by Catholic theologians. One point of objection to
Aristotle was his notion that the universe was eternal, which denied the
act of God’s creation; another was the determinism of his doctrine of
cause and effect, which left no room for divine intervention or other
miracles. Still another objection was that Aristotle’s natural philosophy
was pantheistic, identifying God with nature, which derived from the
Neoplatonic interpretation of Aristotelianism by Avicenna.
This led to a decree, issued by a council of bishops at Paris in 1210,
forbidding the teaching of Aristotle’s natural philosophy in the university’s faculty of arts. The ban was renewed in 1231 by Pope Gregory
IX, who issued a bull declaring that Aristotle’s works on natural philosophy were not to be read at the University of Paris ‘until they shall
have been examined and purged from all heresy.’ The ban seems to

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OF

KRAKOW

have remained in effect for less than half a century, for a list of texts
used at the University of Paris in 1255 includes all of Aristotle’s available works.
Meanwhile European scholars were absorbing the Graeco-Arabic
learning that they had acquired and used to develop a new philosophy
of nature, which although primarily based upon Aristotelianism differed from some of Aristotle’s doctrines right from the beginning.
The leading figure in the rise of the new European philosophy of
nature was Robert Grosseteste (c.1168–1253). Born of humble parentage in Suffolk, England, he was educated at the cathedral school at
Lincoln and then at the University of Oxford. He taught at Oxford
and went on to take a master’s degree in theology, probably at the
University of Paris. He was then appointed Chancellor of the University
of Oxford, where he probably also lectured on theology, while beginning his own study of Greek. When the first Franciscan monks came to
Oxford in 1224 Grosseteste was appointed as their reader. He finally
left the university in 1235 when he was appointed Bishop of Lincoln,
his jurisdiction including Oxford and its schools.
Grosseteste’s writings are divided into two periods: the first when
he was chancellor of Oxford, and the second when he was bishop of
Lincoln. His writings in the first period include his commentaries on
Aristotle and the Bible and most of his independent treatises, while
those in the second period are principally his translations from the
Greek: Aristotle’s Nichomachean Ethics and On the Heavens, the latter
along with his version of the commentary by Simplicius, as well as several theological works.
Grosseteste’s commentaries on Aristotle’s Posterior Analytics and
Physics were among the first and most influential interpretations of
those works. These two commentaries also presented his theory of
science, which he put into practice in his own writings, including six
works on astronomy and one on calendar reform, as well as treatises
entitled The Generation of the Stars, Sound, The Impressions of the Elements,
Comets, The Heat of the Sun, Color, The Rainbow and The Tides, in which
he attributed tidal action to the moon.
Grosseteste was the first medieval scholar to deal with the methodology of science, which for him involved two distinct steps. The first
was a combination of deduction and induction, which he termed
‘composition’ and ‘resolution,’ a method for arriving at definitions.

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The second was what Grosseteste called verification and falsification,
a process necessary to distinguish the true cause from other possible
causes. He based his use of verification and falsification upon two
assumptions about the nature of physical reality. The first of these
was the principle of the uniformity of nature, in support of which he
quoted Aristotle’s statement that ‘the same cause, provided that it
remains in the same condition, cannot produce anything but the same
effect.’ The second was the principle of economy, which holds that
the best explanation is the simplest, that is, the one with the fewest
assumptions, other circumstances being equal.
Grosseteste believed that the study of optics was the key to an understanding of the physical world, and this gave rise to his Neoplatonic
‘Metaphysics of Light.’ He believed that light is the fundamental corporeal substance of material things and produces their spatial dimensions,
as well as being the first principle of motion and efficient causation.
According to his optical theory, light travels in a straight line through
the propagation of a series of waves or pulses, and because of its rectilinear motion it can be described geometrically. His researches on
optics include a study of the focusing of light by a ‘burning glass,’ or
spherical lens, which led him to predict the invention of the telescope
and the microscope. ‘This part of optics,’ he said, ‘when well understood, shows us how we may make things a very long distance off appear
as if placed very close [. . .] and how we may make small things placed
at a distance appear any size we want, so that it may be possible for us
to read the smallest letters at incredible distances, or to count sand, or
grains, or seeds, or any sort of minute objects.’
Grosseteste also wrote a number of treatises on astronomy. The most
important of these was De sphaera, in which he discussed elements of
both Aristotelian and Ptolemaic theoretical astronomy. He also suggests of Aristotelian and Ptolemaic astronomy in his treatise on calendar reform, Compotus, where he used Ptolemy’s system of eccentrics and
epicycles to compute the paths of the planets, though he noted that
‘These modes of celestial motion are possible, according to Aristotle,
only in the imagination, and are impossible in nature, because according to him all nine spheres are concentric.’ Grosseteste also suggests
of astrological influences in his treatise On Prognostication, but he later
condemned astrology, calling it a fraud and a delusion of Satan.

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Grosseteste’s De sphaera was written at about the same time as a treatise of the same name by his contemporary John of Holywood, better known by his Latin name, Johannes de Sacrobosco. Sacrobosco’s
fame is principally based on his De sphaera, an astronomy text based
on Ptolemy and his Arabic commentators, most notably al-Farghani.
The text was first used at the University of Paris and then at all schools
throughout Europe, and it continued in use until the late seventeenth
century.
Grosseteste’s most renowned disciple was Roger Bacon (c.1219–92),
who acquired his interest in natural philosophy and mathematics while
studying at Oxford. He received an MA either at Oxford or Paris, c.1240,
after which he lectured at the University of Paris on various works of
Aristotle. He returned to Oxford c.1247, when he met Grosseteste and
became a member of his circle.
Bacon appropriated much of Grosseteste’s ‘Metaphysics of Light’ as
well as his mentor’s emphasis on mathematics, particularly geometry.
But he does go beyond Grosseteste in his commentary on Alhazen,
particularly his theory of the eye as a spherical lens, basing his own
anatomical descriptions on those of Hunayn ibn Ishaq (808–73) and
Avicenna. Bacon also predicted the invention of wondrous machines
such as self-powered ships, submarines, automobiles and airplanes, writing that ‘flying machines can be constructed so that a man sits in the
midst of the machine revolving some engine by which artificial wings
are made to flap like a flying bird.’
Another pioneer of the new European science was Jordanus
Nemorarius (fl. c.1220), a contemporary of Grosseteste’s. Jordanus
made his greatest contribution in the medieval ‘science of weights’
(scientia de ponderibus), now known as ‘statics’, the study of forces in
equilibrium. One of the concepts he introduced was that of ‘positional
gravity’ (gravitas secundum situm), which he expressed in the statement
that ‘weight is heavier positionally, when, at a given position, its path of
descent is less oblique.’ An example would be a block on an inclined
plane, whose apparent weight, the force with which it presses against
the surface, is greater if the angle of inclination is less. This is equivalent to resolving the weight into two components, one perpendicular to
the plane, which is the apparent weight or ‘positional gravity,’ and the
other parallel to the surface.

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During the second quarter of the fourteenth century a group of
scholars at Merton College, Oxford, developed the conceptual framework and technical vocabulary of the new science of motion. The most
important were Thomas Bradwardine (c.1290–1349) and William
Heytesbury (fl. 1330–9), who continued the Oxford tradition in science initiated by Robert Grosseteste.
Bradwardine’s principal work is the Tractatus Proportionum, completed in 1328. The problem that Bradwardine tried to solve in this
work was to find a suitable mathematical function for the Aristotelian
law of motion, which states that the velocity (v) of an object is proportional to the power (p) of the mover divided by the resistance
(r) of the medium. Bradwardine focused on the change in velocity.
Heytesbury, in his Regulae, defined uniform acceleration as motion
in which the velocity is changing at a constant rate, either increasing or decreasing. For such motion he defined acceleration as the
change in velocity in a given time, which would be negative in the
case of deceleration. He also introduced the notion of instantaneous
velocity, for example, the speed at a particular moment, defining it
as the distance travelled by a body in a given time if it continued to
move with the speed that it had at that moment. He showed that,
for uniformly accelerated motion, the average velocity during a time
interval is equal to the instantaneous velocity at the mid-point of that
interval. This was known as the Mean Speed Rule of Merton College,
which was adopted by Heytesbury’s successors at both Oxford and
Paris.
Advances were also made at the University of Paris by Jean Buridan
(c.1295–c.1358) and his student Nicole Oresme (c.1320–82).
Most of Buridan’s extant writings are commentaries on the works
of Aristotle. His most important contribution to science is his so-called
impetus theory, the revival of a concept first proposed in the sixth century by John Philoponus. He explains the continued motion of a projectile as being due to the impetus it received from the force of projection,
and which ‘would endure forever if it were not diminished and corrupted by an opposing resistance or something tending to an opposed
motion.’ Buridan defines impetus as a function of the body’s ‘quantity
of matter’ and its velocity, which is equivalent to the modern concept of
momentum, or mass times velocity, where mass is the inertial property

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of matter, its resistance to a change in its state of motion. As applied
to the case of free fall, Buridan explains that gravity is not only the
primary cause of the motion, but also imparts additional increments
of impetus to the body as it falls, thus accelerating it, that is, increasing
its velocity.
In one of Buridan’s Aristotelian commentaries he asks if a proof
can be given for Aristotle’s geocentric model, in which the earth is
at rest at the centre of the cosmos with the stars and other celestial
bodies rotating around it. He notes that many in his time believed the
contrary, that the earth is rotating on its axis the cosmos with the stars
and other celestial bodies rotating around it. He notes that many in his
time believed the contrary, that the earth is rotating on its axis and that
the stellar sphere is at rest, adding that it is ‘indisputably true that if
the facts were as this theory supposes, everything in the heavens would
appear to us just as it now appears.’ In support of the earth‘s rotation,
he says that is better to account for appearances by the simplest theory,
and it is more reasonable to think that the vastly greater stellar sphere
is at rest and the earth is moving, rather than the other way around.
But, after refuting the usual arguments against the earth’s rotation,
Buridan says that he himself believes the contrary, using the argument that a projectile fired directly upward will fall back to its starting
point, which is true, at least approximately, whether or not the earth
is rotating.
Oresme’s researches on motion are described in his Tractus de
configurationibus qualitatum et motuum, in which he gives a graphical
demonstration of the Merton Mean Speed Rule. The graph plots the
velocity (v) on the vertical axis as a function of the time (t) on the
horizontal axis, as, for example, in the case of a body starting from
rest and accelerating so that its velocity increases by 2 feet per second
every second. Graphing the motion for 4 seconds, the velocity increases
each second from 0 – 2 – 4 – 6 – 8 feet per second at the end of 4 seconds. This plots in the form of a straight line rising from 0 to 8 feet
per second over a time interval of 4 seconds, forming a right triangle
with a height of 8 and a base of 4. The acceleration (a) is equal to
the slope of the straight line, which is 8/4, or 2, in units of feet per
second per second. The average velocity is half of the final velocity,
which is 8/2, or 4 feet per second. The Mean Speed Rule then gives

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the distance travelled in 4 seconds as 4 × 4, or 16 feet. The rule can
be applied over each one-second interval, so that the average velocity
for each second increases from 1 – 3 – 5 – 7 feet per second. The distance in feet travelled in the first second is then 1, in th