The Embryological Background

The aim of this chapter is to examine Plato’s remarks pertaining to embryology, which are almost entirely contained in the Timaeus, and to set out his views in as much detail as the texts permit. In this way, when we turn to the Neoplatonists we will be in a better position to evaluate to what extent their theories are fair representations, or at least fair developments, of Plato’s theory. This examination of Plato will be facilitated by a brief overview of four key issues in ancient embryology, namely the three major issues in spermatogenesis ¹ – the number of seeds involved in reproduction, the corporeal origin of the seed, the manner in which the offspring is present in the seed – along with the moment of animation of the offspring. As we shall see, these are all issues that were widely discussed by both philosophers and physicians in antiquity, and so we can reasonably expect Plato to have been familiar with them and to be addressing them in the Timaeus (or else to be consciously avoiding them). To be sure, these four issues are far from exhausting the scope of ancient embryology. The list of embryological questions collected by Aëtius gives a sense of some of the issues being left out of this overview, e.g. how twins are formed, how the offspring’s sex is determined, and how to account for deformities and (lack of) resemblance. ² Although we shall see that Neoplatonists did concern themselves with some of these other issues, their interest in them was limited and Plato does not incorporate them into his account at all. We can therefore leave these other questions aside for now. In the next chapter we shall have the opportunity to explore a further key issue in ancient embryology, namely the causal factors involved in embryogenesis, but since this is again a topic on which Plato has little to offer its discussion may be postponed.