I think you too recognize the important relationship between philosophy and art, and it is just this relationship that most painters deny. The great masters do grasp it, unconsciously; but I believe that a painter's conscious spiritual knowledge will have a much greater influence upon his art, and that it would be due only to a weakness in him, or lack of genius, should this spiritual knowledge be harmful to his art...
The new art--the new life: the collected writings of Piet Mondrian (ed. Twayne Pub, 1986)