There are only two places in which Plato explicitly offers a critique of the sort of theory of forms presented in the Phaedo and Republic: at the beginning of the Parmenides and in the argument against the Friends of the Forms in the Sophist. An accurate account of the argument against the Friends, therefore, is crucial to a proper understanding of Plato’s metaphysics. How the argument against the Friends ought to be construed and what it aims to accomplish, however, are (...) matters of considerable controversy. My aim in this article is twofold. First, I show that the two readings of the argument against the Friends that dominate the contemporary literature – the “Cambridge Change” reading and the “Becoming-is-Being” reading – lack sufficient textual support. Second, I offer an alternative reading of the argument against the Friends that better explains both the text of 248a4–249d5 and the role the argument plays within the Stranger’s wider project of demonstrating that non-being is. My thesis is that the Stranger’s argument against the Friends seeks to demonstrate that the forms must be both at rest and moved, where “moved” has the sense of “affected.” To participate in a form is to be affected by that form. I argue that since, according to the Stranger, every form participates in some other forms, every form is “moved” in the sense that it is affected by the forms in which it participates. Likewise, I argue that every form is at rest in the sense that its unique nature remains unaffected by the other forms in which it participates. (shrink)