This article argues for an emendation in Aristotle's Metaphysics A 10, 993a13–15. The emendation is based on a hitherto overlooked reading preserved in Alexander of Aphrodisias’ commentary on A 7. First, the article problematizes the reading of the Metaphysics manuscripts in terms of syntax, diction and content. Second, it shows that Alexander's reading is free of all three problems. Third, it argues for the originality of Alexander's reading according to the principle utrum in alterum abiturum erat? and based on the fact that the new reading reveals a subtle didactic link between A 7 and A 10 that sheds new light on the argumentative architecture of Metaphysics Book A.