something matisse wrote i keep rereading:

"if, on a clean canvas, i put at intervals patches of blue, green and red, with every touch that i put on, each of those previously laid on loses in importance. say i have to paint an interior; i see before me a wardrobe. it gives me a vivid sensation of red; i put on the canvas the particular red that satisfies me. a relation is now established between this red and the paleness of the canvas. when i put on besides a a green, and also a yellow to represent the floor, between this green and the yellow and the color of the canvas there will still be further relations. but these different tones diminish one another. it is necessary that the different tones i use be balanced in such a way that they do not destroy one another. to secure that, i have to put my ideas in order; the relationships between tones must be instituted in such a way that they are built up instead of knocked down."