In ‘Platonist Notions and Forms’, Mauro Bonazzi explores an aspect of the Platonists’ engagement with Stoic epistemology, namely the Platonists’ appropriation of the Stoic ennoiai, conceptions or notions, to show that Plato’s doctrine can provide a satisfactory answer to the problem of the foundation of knowledge, which Stoicism has proved unable to solve. The Stoic ennoiai, (conceptions) or phusikai ennoiai (natural conceptions) are notions naturally arising in the human mind and constituting the basic elements of human reason. They are ‘natural’ in the sense that humans are naturally disposed to acquire them, and they are koinai (common) in the sense that all humans have them or are disposed to have them. They are also invariably true and therefore can serve as criteria in order to increase knowledge, promote scientific understanding and contribute to the good life. It is these ennoiai that the Platonists integrate in their own reinvention of Plato’s epistemology and employ in their polemics against their principal rivals.

This chapter discusses the importance of rhetoric to the rise of the Sophists and the way that an attention to language as such conduces to a novel and controversial understanding of reality. Language, for the Sophists, is more than a medium for conveying meaning; it is itself creative of meaning, making the education that they offer uniquely powerful. This is the fuller sense of their professing to make their students “clever at speaking” (deinos legein). The chapter traces three specific areas on which the Sophists brought to bear their interest in logos: grammar and the issue of the correct names; the criticism of and engagement with poetry; and rhetoric and the effectiveness of argumentative techniques. We see that these explorations cannot be said to aim at a systematic theory. But they helped to inaugurate the study of language for its own sake, a topic that would play an important role in the philosophical debates of the following centuries.

At their first meeting, Porphyry took Plotinus for ‘a complete fool’ and a sophist. This reaction was by no means exceptional.1 The leading Platonists of the time, most notably Longinus, misclassified Plotinus as a representative of an Oriental, Pythagoreanizing version of Platonism.2 Admittedly, it was not easy to understand the novelty of his views. At stake in the discussions with Porphyry and Longinus was the claim that the intelligibles are not outside the Intellect. Marginal as it might appear at first sight, Plotinus’ thesis actually paved the way to a new interpretation of Plato’s Forms, the kernel for any Platonist system. After an intense exchange, Porphyry ‘finally managed to understand what he was saying’,3 wrote a retraction, and became one of his most faithful pupils for the years to come. Most of the other Platonists, however, continued to endorse their traditional interpretation. But in the meantime, the history of ancient Platonism had entered a new phase.