Abstract
Commentators are divided on the interpretation of Metaphysics Z4 1029b13–22. For one thing, it is unclear whether the passage rejects a claim about the essence of surface, or about the essence of pale. It is usually thought that the claim is disavowed because it involves a circular definition. However, this is conjectural, since Aristotle does not explicitly say anything about circularity in the lines in question. I argue here for an alternative account, which reads the disputed lines as an extension of the immediately preceding remarks. If correct, this also solves the problem as to just what Aristotle is denying. As will emerge, my story is helped by St. Thomas’ reading of lines 21–22, an account that has been curiously ignored in the recent literature.