If my contention [that different forms arise in identical environments] is in accord with the facts, the assumption which we often meet that change in the organism is controlled in all its details by change in the environment, and that, therefore, human progress is ruled by an external fate, is certainly contrary to fact.

Evolution, Racial and Habitudinal: Racial & Habitudinal, Preface (p. iv), Carnegie Institution of Washington. Washington, D.C. 1905