John Cage's Color and Meaning: Art, Science, and Symbolism (California, $55) is a magical mystery tour through that which we hold familiar. Among other things, Cage puts under his mind's prism our system for categorizing color, which we cling to despite optical evidence. For example, if you stare at the red disk then go to the white, you'll probably see an afterimage that you'd describe as "blue-green," yet since the 1800s red's so-called complement has been simply green. Pre-Columbian peoples never discriminated between blue and green; to them, this turquoise Mixtec mask was green. In Crystal Garden, Paul Klee toyed with a red-to-green color scale. (The philosopher Wittegenstein called a red-green color step a "logical impossibility.") An early color scale for painters shows the influence of Newton's spectrum on artists.