Painting is something that takes place among the colors, and … one has to leave them alone completely, so that they can settle the matter among themselves. Their intercourse: this is the whole of painting. Whoever meddles, arranges, injects his human deliberation, his wit, his advocacy, his intellectual agility in any way, is already disturbing and clouding their activity.

Letter to his wife, reprinted in Rilke's Letters on Cézanne (1952, trans. 1985). (October 21, 1907) - Rilke's Letters