Celsus is important evidence for Middle Platonist thought over the nature of the demiurge. This paper argues that he identified the demiurge with an impersonal first principle, the form of the good. In showing how the evidence for Celsus helps to explain the metaphysics at work in this model, it aims to remove doubt that it is a model widely shared by other Platonists.

How is the rationality of the Stoic god constituted? Commentators often look to the seventeenth-century ‘rationalists’, especially Spinoza, for their inspiration. But the Stoics say that god’s rationality is the same as ours. Since human rationality is defined as a product of concept-acquisition, it may be that the Stoics had to give an ‘empiricist’ account of divine rationality too. Hierocles’ discussion of animal self-perception shows that the Stoics had the conceptual materials for such an account.

Emphasis on the ‘craftsmanlike’ character of creation in the Timaeus can give the impression that the cosmos is no more an ‘animal’ than Dr Frankenstein’s monster. But Middle Platonists took more seriously the biological implications of the claim that the god is the world’s father as well as its maker, implanting a soul in matter which (as in all animals) brings the cosmos to maturity through its own creative agency. Entailments of the view are that the world soul is first and foremost the ‘nutritive’ soul of the cosmos and that the soul must be a structural feature of the cosmic body rather than a distinct substance.

In his seminal article on philosophical authority published in 1997, David Sedley showed that, in antiquity, the founder of a philosophical school was taken as figure of ‘authority’ by subsequent members of the school, who would carefully avoid expressing disagreement with him. What is more, the reason for their deference was not purely formal, or political: the authority with which school-members invested the founder of their school was epistemic as well, in the sense that it involved some level of concern to know and be guided by their founder’s views. But this is far from the end of the story. As Jan Opsomer and Angela Ulacco have been careful to describe subsequently, ‘epistemic authority’ ranges widely in sense and strength: from uncritical assent to the truth of whatever can be gleaned from the authority-figure within a given domain, to the belief that their views might help to point one in the right direction.1 Where one stands on this question might make all the difference to the character of one’s philosophical project.

This chapter argues that Plato effectively pre-empts the Stoics in defining virtuous action as conformity with cosmic order. Scholarship has been beguiled by Alcibiades’ striking analysis of Socrates in the Symposium as someone ugly to look at but beautiful within, and misled into thinking that Plato defines virtue as ‘inner beauty’, something private which only accidentally manifests itself in public benefit. In fact, as a closer examination of Diotima’s account of the lover’s ascent towards beauty in the same dialogue shows that the distinction that actually interests Plato is that between the body and its activity – not the body and the soul as such. And by referencing this activity to cosmic order (as he does most clearly in Gorgias 507e-508), Plato guarantees essentially that virtue is not only publicly manifest but of essential benefit to others as well as self.