On 5 October 1971, I wrote a short paper on Metaphysics 1004b25–6, for a tutorial with G. E. L. Owen at Harvard.Since then I have intermittently pursued some lines of inquiry connected with that passage; the current result of themis this book. The first chapter gives a survey of its contents, and some idea of the main argument. I try to explore someconnexions between different areas of Aristotle's philosophy, and to suggest how issues and doctrines in one area mayaffect his views in another. Whether or not the main thesis of this book is found convincing, I hope it will seemprofitable to examine some of the connexions I discuss, and to see how they affect our views about the coherence andplausibility of Aristotle's doctrines.While I would like to have formed original and convincing views on all the questions I discuss, I cannot claim to havedone this. On many points I rely on views that other people have made quite familiar (though hardly standard, giventhe extent of healthy disagreement in the study of Aristotle). On the other hand, though I cover more topics than areusually covered in a single book on Aristotle, this book is not a general survey; it is quite selective, and it does notattempt to give a balanced impression of Aristotle as a whole. Still, I hope I have provided enough detail to give theuninitiated reader some idea of the main questions, and of some of the main approaches to them, and also to give boththe less advanced and the more advanced student some idea of the reasons for my conclusions. While this is not anintroductory book, I hope it will be accessible to reasonably persistent readers who have not read much aboutAristotle, but are willing to read Aristotle fairly closely; in the main text I try not to presuppose familiarity with thepresent state of scholarly and philosophical discussion.The notes discuss some points of detail, and indicate some of my views on issues that have been discussed by otherwriters on Aristotle. They come after the main text, on the assumption that many readers will find it easier to read themain text before tackling the issues that are raised in the notes. The general excellence of the ‘secondary literature’ onAristotle, extending from the Greek commentators to the present, is unrivalled (as far as I know) by what has beenwritten on any other philosopher; and therefore I would like to have done more justice to it than I have. The readershould not anticipate the systematic and judicious selection that would certainly be desirable. I especially regret thebrevity of my discussion of some complex issues and of the views