Let's go back to your dream of being the next Picasso. Painting is a very complex task: you have to think about what you're going to paint, imagine how you want it to look, plan the style of the painting, figure out what tools and processes you need to paint the piece... And all that's before you even begin to paint!
Wundt called the process of controlling and organizing thoughts into higher-level processes (like painting or thinking about hypothetical situations) voluntarism. You're able to voluntarily control your thoughts to accomplish something difficult. One way of doing this is through apperception, or the way a person uses his or her previous knowledge and experience to understand what he or she is perceiving. If you see a dog, you can use your previous understanding about dogs to recognize that it's a dog and to figure out if it's friendly or hostile. Likewise, you can use your previous understanding about painting to help you assess your own painting.
Apperception and voluntarism were important ideas. Wundt was basically arguing that people are able to control and direct their thought processes. Remember how we said that mental systems are hierarchical? That is, how we said something like painting is more complex than simply perceiving color? We can only move to the high end of the hierarchy and perform complex mental processes if we're able to direct and control our thinking.
Wundt also offered one of the first theories about emotion. His tridimensional theory of feelings says that all feelings fall somewhere on three scales: excitement-calm, pleasure-displeasure, and tension-relaxation. For example, think about how you might feel if you've just completed a masterpiece painting. You'd probably feel thrilled! That feeling, that thrill, is likely composed of excitement, pleasure, and tension. That is, you're happy and wired! In contrast, something like depression might be made up of calm, displeasure, and relaxation. You're feeling down in the dumps, which isn't fun, and low energy.
