Where’s the natural in a painting? Everything in paintings since the most distant ages has been completely conventional, deliberate throughout and very far from the natural, consequently very mannered. You’ll say that they, the ancient masters, have genius. That’s true, and we don’t have it, but that’s no reason not to proceed like them. To a Japanese person what we do is mannered and vice versa; this comes from the fact that there’s a notable distance between the two in vision, customs and types. So if a man sees, feels, thinks differently from the mass because of race, temperament or other cause, he is unnatural and consequently mannered.
Paul Gauguin
Letter to Vincent van Gogh, 13 December 1889