Speaking for myself, art differs from writing in that I never know what I'm going to paint until I paint it, so it's almost like automatic writing. A writer, on the other hand, can't help but know what he's going to write, because the activity demands a degree of premeditation.
Burroughs Live: The Collected Interviews of William S. Burroughs, 1960-1997 (ed. Semiotext, 2001)