I like this particular chart of the emotional, physical, and behavioral effects of different colors, but the whole post is one of the best explanations of color I've seen. Explanations here for primary, secondary, and tertiary colors, as well as complementary, analogous, triadic, and warm/cool colors.
Man at the dawn of civilization recognized that sunlight was essential to life. Color, being a manifestation of light, held divine meaning. Historical records of color show little interest in the physical nature of color, nor yet in its abstract beauty, but in symbolism that attempted to resolve the strange workings of creation and give it personal and human meaning. —Faber Birren