Aristotle's was until recently treated as a poor cousin of the better-known - poor enough even to have to borrow its three central books (IV-VI) from the latter. The work has now emerged from its relative obscurity; many scholars, indeed, now claim - on the basis of what appear to be sound statistical arguments - that it is the that has to borrow its Books V-VII from the . is a companion volume to the critical edition of Aristotle's in the Oxford Classical Text series, edited by Christopher Rowe. The companion text explains the principles of the critical edition, justifying individual readings in detail, and providing information about the Greek manuscripts. An appendix brings together full datasets for the four primary manuscripts that reveal not only the relationships between them, but also the idiosyncrasies of the three copyists involved, and the typical errors that tend to be found in the different manuscripts.