Through this sixth-century Neoplatonist commentary on Aristotle, I follow the insights of the French scholar Pierre Hadot to discuss the nature of orality in ancient Greek philosophy, specifically in the thought of Plato. Plato’s attitude to written texts was ambivalent: despite finding them sometimes useful, he seems to have considered them open to misinterpretation and ultimately inadequate. In order to achieve their intended impact, philosophical arguments, discussions, and dialogues (in ancient Greek: logoi) had to take place face-to-face between teacher and disciple. I examine the theoretical presuppositions underlying this view of the superiority of oral discourse. For Plato and his Neoplatonic exegetes, what was the nature of the transformational impact that the Greek words spoken by a teacher had on a well-disposed student? Was it purely rational, or did it implicate other human faculties? Were words of the Greek language thought to exert some kind of semi-magical effect on the minds and souls of listeners by their very nature, or were they ineffective unless connected to the meaning they were intended to transmit? Finally, what implications do these questions have for the way we read, study, and teach Greek philosophy today?