The study of contemporary species does not establish the existence of evolution; it provides facts which support it, but which do not fully demonstrate its existence. This is understandable, since at present we cannot show the series of successive stages which make up evolution, but only a fleeting picture of evolution.

Grassé, Pierre Paul (1977); Evolution of living organisms: evidence for a new theory of transformation. Academic Press, p. 3 - Evolution of living organisms: evidence for a new theory of transformation (1977)