Suppose a painter sees a path through a field sown with poppies and paints it: at one end of the chain of events is the field of poppies, at the other a canvas with pigment disposed on its surface. We can recognize that the latter represents the former, so I shall suppose that despite the differences between a field of poppies and a piece of canvas, despite the transformation that the artist has effected in what he saw to make it take the form of a picture, something has remained unaltered and on this something recognition depends. The elements that go to make up the unaltered aspect of the transformation I shall call invariants. [Bion, 1965, p. 1]