Beginning, roughly in 1955, after a period of painting direct, simple images as statement (Tableau Vivant; The Blue Waltz; Death and the Maiden...), my painted compositions began to shift and merge in an ever intensifying complexity of planes. Color was now a first prerogative: a white canvas tacked to the wall in Sedona would be blue and violet and a certain dried rust-red.  It would have to be vertical. It would also be not quite there, immediately. I wanted to lead the eye into spaces that hid, revealed, transformed all at once and where there would be some never-before-seen image, as if it had appeared with no help from me. I was very excited and called it Insomnias. 

     —from Between Lives: An Artist and Her World. New York: W.W. Norton & Company, 2001, pp. 213-214.