The paper analyses the argumentative structure of a difficult passage from Aristotle's Metaphysics XII 7 on the basis of a topos of sameness provided in Top. VII 1. In doing this the article gives an example of how Aristotle's treatises on dialectic can prove useful to understand what he says in his more philosophically committed writings. The article also shows how general argumentative techniques and more or less explicit specific philosophical assumptions interact in shaping Aristotle's arguments and how the distinction (...) of these different factors can help us have a better grasp on Aristotle's text. (shrink)