He succeeds in being both a pragmatist and a dreamer, equally inclined to the rational and the intuitively irrational. ‘When reason sleeps, the sirens sing,’ said Max Ernst (incidentally also a lover of glaze painting). Rationality and irrationality belong together for Willi Keller like day and night. His pictorial themes fall to him. Never are they thought up or consciously worked out.”
Peter Killer, art critic, director of the Kunstmuseum Olten 1983 – 2001.