The Thinking Eye is an intriguing book showing, through records of lessons Klee taught at the Bauhaus, the impressive depth of his artistic philosophy. He employs a rather reductive approach to create his very personal understanding of art. Whereas most artists are concerned primarily with having a working, utilitarian knowledge of aspects such as perspective, colour, composition, etc., Klee gives a large amount of thought to more basic, and seemingly simple, elements such as the point, the line, the surface. The Thinking Eye is a great read if you love the conceptual side of art and if you have a decent tolerance of dense topics.