Paul Klee (1879-1940)

"Color has taken possession of me; no longer do I have to chase after it, I know that it has hold of me forever. That is the significance of this blessed moment. Color and I are one. I am a painter."

As an artist with great skill with color, he was also a great teacher at color mixing and theory. He wrote his great treatise, a collection of lectures, entitled Writings on Form and Design Theory, which is considered one of the most influential writings in modern art. 

Klee was a violinist- music heavily influenced his artwork (for example, the second painting here is called "ancient sound"). You can definitely feel a sense of fluidity in many of his paintings, similar to that of music.  He considered himself more of an artist than a musician, because art allowed him to explore more radical and free ideas. 

He worked a lot with mixed media, and often incorporated many materials into one work of art (for example, the second painting shows the use of gauche, watercolors, and linen, and the second painting is oil on cardboard)