All the secret of paint is locked up in the painter who starts from the bottom and works to the top, and then works down from the top to the bottom, making triumph after triumph and mistake upon mistake, covering up both mistakes and triumphs with more paint of different colors—blue, green, yellow, red, white, and their offshoots—until the purity of the painter’s original vision is diverted into a new purity, a colorful paradise in which the paint itself, not the painter, is in control, and the painter must resist the temptation, as strong as it might be, of mixing a light green wash in a bucket of cold tap water and pouring the whole thing over the painting that the paint has just created.