"The only valid thing in art is that which cannot be explained. To explain away the mystery of a great painting – if such a feat were possible – would be irreparable harm.. .If there is no mystery then there is no 'poetry', the quality I value above all else in art. What do I mean by 'poetry'? It is to a painting what life is to man.. .For me it is a matter of harmony, of rapports, of rhythm and – most important for my own work – of 'metamorphosis'"