1. In my book, Aristotle's Classification of Animals I tried to show that there is no room at all for any animal taxonomy in the Aristotelian biological project. The various orderings of animals which we find in Aristotle are always relative to the point of view and the immediate objective of the inquiry at hand. Thus Aristotle can at one time order animals according to the growing complexity of their reproductive organs, at another according to the form and disposition of their nutritive organs. Certainly it seems obvious to us that such studies presuppose a distribution of animals into stable and recognized families. That is not how it is for Aristotle, and I tried to present the status, in the biological works, of his various classifications, relative to his different inquiries, none of which is able to claim priority over the others; these are purely empirical procedures, meant to facilitate the work of the biologist, but they remain outside properly epistemic research. I claim that the retrospective projection of the theoretical presuppositions of ‘classical’ natural history onto Aristotelian biology has prevented the best interpreters, and a fortiori the lesser, from grasping the exact functioning of these concepts in that biology. That is true of the notions of genos and eidos and of the relationships which, so to say, follow these two concepts, in particular the relation of analogy.