Whatever the difficulties inherent in the conception of an evolutionary ethic, it might be thought that any involutionary morality must necessarily be ‘closed’, in the Bergsonian sense of the word. Reason, one might argue, will want to schematize situations and human responses to them, and will accordingly busy itself with the formulation of precepts. It will be easy to slip from this assumption to the further assumption that assimilation works against individuality and favours authority and uniformity. I think, in fact, that the existentialist complaint against reason and rationalist ethics amounts to saying that it stifles individuality and makes conformists of us all. But Lalande’s thesis does not bear this out; his morality of involution is not the answer to a dictator’s prayer. Indeed he attacks Renan’s Dialogues philosophiqes for the much-discussed passage in which Renan supposes the end of the evolutionary process to be the concentration of all matter into a single, all-embracing living organism.1 This, of course, is genuine evolutionism (carried, it is true, on to a metaphysical plane) as Lalande has defined it, for a single expansive and acquisitive will is imagined as having prevailed over all matter and drawn it into its service. Moreover since, in Renan’s image, we are presented with the apotheosis of assimilation, one being absorbing all things, it is desirable to clarify Lalande’s conception of involution.