The topic of my talk is a very ancient one indeed. It bears upon the place of humankind in nature, and upon the place of nature in ourselves. I shall, however, be discussing this range of questions in terms which have not always been available to the philosophers of the past when they have asked them. When we ask these questions today we do so with hindsight of some two centuries of endeavour in the ‘human sciences’, and some one and a half centuries of attempts to situate the human species within a theory of biological evolution. And these ways of thinking about ourselves and our relation to nature have not been confined to professional intellectuals, nor have they been without practical consequences. Social movements and political organizations have fought for and sometimes achieved the power to give practical shape to their theoretical visions. On the one hand, are diverse projects aimed at changing society through a planned modification of the social environment of the individual. On the other hand, are equally diverse projects for pulling society back into conformity with the requirements of race and heredity. At first sight, the two types of project appear to be, and often are, deeply opposed, both intellectually and politically.