The “battle” between corporealists and idealists described in Plato’s Sophist 245e6-249d5 is of significance for understanding the philosophical function of the dramatic exchange between the Eleatic guest and Theaetetus, the dialogue’s main interlocutors. Various features of this exchange indicate that the Eleatic guest introduces and discusses the dispute between corporealists and idealists in order to educate Theaetetus in ontological matters. By reading the discussion between Theaetetus and the Eleatic guest in the light of these features, one comes to see that the primary audience for the proposal advanced by the Eleatic guest in this passage, namely that being is power, is not any of the participants in the “battle,” as has been commonly assumed, but Theaetetus himself—a fact to bear in mind in any viable interpretation of the passage.