This is what happens, unquestionably – I am positive: an optical sensation is produced in our visual organ, which leads us classify as light, half-tone or quarter-tone, the planes represented by sensations of color. [Thus the light does not exist for the painter]. As long as, inevitably, one proceeds from black to white, the former of these abstractions being a kind of point of rest both for eye and brain, we flounder about, we cannot achieve self-mastery, get possession of ourselves. During this period (I tend to repeat myself, inevitably) we turn to the admirable works [of the five great Venetian painters a. o. Titian and Tintoretto] handed down to us through the ages, in which we find comfort and support...

In: a letter to Émile Bernhard, 23 December 1904, as quoted in Letters of the great artists – from Blake to Pollock, Richard Friedenthal, Thames and Hudson, London, 1963, p. 184 - after 1900