I have such a passion for painting! I am continually working at form. In actual drawing and in my head, and during my sleep. Sometimes I think I shall go mad, this painful, sensual pleasures tires and torments me so much. Everything else vanishes, time and space, and I think of nothing but how to paint the head of the resurrected Christ... Or how shall I paint Minkchen [his wife Minna] now, with her knees drawn up and her head leaning on her hand against the yellow wall with her rose, or the sparkling light in the dazzling whiteness of the anti-aircraft shell-bursts in the leaden, sun drenched sky...

In: a letter to his first wife Minna, from the front, first World war, 11 May, 1915; as quoted in Letters of the great artists – from Blake to Pollock, Richard Friedenthal, Thames and Hudson, London, 1963, p. 213