Paul Klee's philosophy of art is perhaps best summed up by his own statement: "A drawing is simply a line going for a walk." As one of the great avant garde artists of the 20th century, Swiss-born Klee was swept along with the changing moods and philosophies of the time. Klee did not readily fit into a particular artistic category. He used many styles and techniques, always exploring the different variations that each media opened up to him. An important element in Klee's work is his use of symbols and words to convey thoughts and philosophies directly on the canvas. To provide the greatest degree of diversification in his creations, Klee habitually used a variety of surfaces on which to paint, not just conventional canvas but also linen and even fine gauze, and sometimes coarse burlap, board, or glass--any textured surface on which color could be applied. Klee's interest, understanding, and analysis of color theory and tone--which he explained in several influential books--arguably left a greater legacy than his artworks.