A. N. Whitehead memorably characterized philosophy as a series of footnotes to Plato. The comment can suggest a picture of philosophy progressing by regular stages, building on a common growing structure. But that is not how Plato has wielded his influence. The correct picture is rather that Plato has been especially influential at certain times and places in the subsequent philosophical history, and in very different ways at these various points. I shall demonstrate this by focusing on four such episodes.

First, the Neoplatonists. They were a school of philosophers, founded by Plotinus, in the third century CE. He established the main philosophical focus of the school, and set them out in the work Enneads, which survives intact. Main figures during its existence over the following three centuries were Porphyry, Proclus, Ammonius and Iamblichus, who claimed to derive their philosophy from Plato, and were especially influenced by his transcendental vision of metaphysics. They regarded the whole of reality as dependent on a single principle: the One. Various lower levels of reality were derived from this supreme being, and each lower level strives to return to the higher state from which it is descended. Plotinus is concerned above all with the nature of the soul and the intellect, and their relations to the highest principle and the Forms and also to the corporeal world.