"Each work of art is a complete entity existing in its own right and by its own particular logic. It has its own reality and is independent of any particular creed or theory as a justification for its existence. This is not to say that artistic development may be considered as a self-sufficient process unrelated to social reality, because art is always concerned with the deeper and fundamentally human things; and any consideration of art is a consideration of humanity. But it does mean that we cannot apply the principles and logic of the past to a new work of art and hope to understand it. The eternal verities with which the artist is concerned do not change, but our conception of art does, as does our conception of form, and these must be extended if we are to understand fully and basically the meaning of a new work. It is a complex matter, but the elemental principles are always simple. The mass of modern art theory that developed around the fantastic changes of this century's painting can be largely ignored; only one or two fundamental principles are important. Probably most important in the new aesthetics from the painter's point of view was the statement of Degas, seventy years ago, in his unheeded advice to the Impressionists. He spoke then of a "Transformation in which imagination collaborates with memory... It is very well to copy what one sees; it is much better to draw what one has retained in one's memory”…This attitude, and all it implies, underlines the work of practically every painter of importance since 1900. Ultimately, it meant that the day of stage props and models was gone, and that imagination was recognised as the most important quality in an artist."