Gauguin, that curious artist, that alien whose mien and the look in whose eyes vaguely remind one of Rembrandt's "Portrait of a Man" in the Galerie Lacaze — this friend of mine likes to make one feel that a good picture is equivalent to a good deed; not that he says so, but it is difficult to be on intimate terms with him without being aware of a certain moral responsibility.

Letter no. 626a (1890), published in The Complete Letters of Vincent Van Gogh, Vol. 3 (1958) New York Graphic Society, p. 256