I painted 'the Shelton with Sunspots' [New York], in 1926. I went out one morning to look at it before I started to work and there was the optical illusion of a bite out of one side of the tower made by the sun, with sunspots against the building and against the sky. I made that painting beginning at the upper left and went off at the lower right without going back.

Some Memories of Drawings (1976)