It would be a sad thing for an artist if he knew how to paint. – so sad. An artist paints because it is a challenge to him – it is like trying to twist the devil. If you overcome it, there is no sport left. I don't even like to talk about painting. It is impossible to talk about painting because I don't know what it is. If I knew what it was I would get out a patent and then no one else would be able to paint.

'A Painter in a Glass House' (1948)