With meticulous theories and many thousands of paintings, drawings, and watercolors, Paul Klee (1879-1940) is considered one of the most cerebral and prolific leaders of 20th-century European art. Though typically small in scale, his works are remarkable for their sophisticated thought and meticulous nuances of line, color, and tonality. Klee's stylistic formation was shaped by early affiliation with the German expressionist group Der Blaue Reiter...