I think a lot about what representational painting is in order to explain it to my students at the Art Center. For a long time in my mind I've tried to work out a "grand unified theory" of color but have never seemed to be able to tie all the ends together into a neat package. Lately however I feel like I've gotten closer than ever. One quote that has always surprised and fascinated me is by van Gogh, "And then I do not know how you will handle your colors, but that matters little. Just continue on: there is no better education than painting outdoors; you must always compare things thoroughly with one another, especially in tone. Painting is like algebra; that is to that as that is to that." I've always found that curious, the 'wild man from Arles' comparing painting to algebra of all things?!? But now I think I'm starting to know what he's talking about... Creating the effect of light and shadow, or chiaroscuro, is a very specific thing the artist is doing with paint. Let me see if I can explain it. Things in the world have a certain actual lightness or darkness to their surface, or "local color". Things can't be whiter than white or blacker than black. The artist only has from white to black (and the range of greys in between) to work with. The artist might be making a painting of a person with a white shirt, fair skin, red vest, and blue jeans... four colors of things that in actuality range in value (or tone) from nearly white to nearly black. They have a certain relationship to each other in terms of value and hue (color) When the artist is creating the effect of chiaroscuro, they are creating two different 'keys' of the same relationship of those four local colors, one in an 'upper' or lighter register (chiaro) and one in a lower or darker register (scuro). When these two sets of local color relationships are placed next to each other, the effect to the viewer is the inescapable appearance of light on form. It's very logical or as Vincent calls it, algebraic. CLICK HERE FOR RELATED LINK