The Platonic corpus as we have it (in the Oxford Classical Text, for instance) reflects a stability dating back at least to the second century A.D. when Thrasylus arranged the material available to him—probably in the Academy library—into groups of four items. We are told of an earlier Alexandrian ordering by trilogies. Some writings which were associated with Plato’s name followed after Thrasylus’ tetralogies, but these can safely be left aside as spurious. Within the scheme of tetralogies we find dialogues (though the Apology is of course a monologue, and so largely are the Timaeus and the Laws; while the Menexenus is a curious speech enclosed in minimal dialogue), letters and ‘definitions’.

It is not possible in so brief a summary to discuss the literature on Socrates or the thought about him at any length. We have had a book by Norman Gulley (The Philosophy of Socrates [London, 1968] ) and Guthrie has devoted the second half of his third volume to Socrates. There has also been lively discussion on certain ‘Socratic’ questions and positions—the unity of αρβτή and the claim ούδείς εκών αμαρτάνει— but these discussions centre rather on the questions in themselves, and the writers accept that Socrates did hold these views and that Plato’s testimony on this can be accepted—with, of course, corroboration by Aristotle.

But this view is not tenable unless one is ready to regard all Western political thought as mistaken. For when Aquinas adapted the basic concepts of Aristotle’s Politics to medieval Christianity and to Christendom, he was taking over Plato’s thought, although in a reduced form. Findlay removes all real concern for human institutions from Plato. Moreover, Augustine’s conception of two cities, one of them heavenly, remained in Europe as a vision, to supplement what Aristotle had reduced and Aquinas had codified.

Interest in Plato Metaphysicus has been as intense, and even more sustained, than interest in Plato Politicus. Some thinkers who might well dislike his political doctrine have found themselves caught up in controversy over his metaphysics, or his discussion of the meaning of the verb ‘to be’. It is a sheer impossibility to present a résumé of the actual discussions in the confined area of a brief summary: all that can be attempted is a chronicle of the issues that have occasioned most controversy in recent years. This will entail crossing dialogue boundaries and treating ‘themes’, though one should remember that each dialogue really has its particular quality and makes its own approach to the question or questions it considers.

The title of this chapter is that of Cornford’s translation of and commentary on the Theaetetus and the Sophistes. It is in the former dialogue that the ‘subjective’ side of the knower-known relation is discussed. Cornford’s view was that the Forms are deliberately excluded by Plato from the Theaetetus in order to show that sensation, opinion, and opinion-plus-definition cannot be knowledge, and therefore that only cognizance by intellect of the Forms can be knowledge. This view has not proved acceptable, though if the dialogue Philosopher had ever appeared (as promised in Sophistes and Politicus) we might well have seen that the Theaetetus did in a sense provide prolegomena to a positive theory of knowledge which entailed some statement also of a doctrine of Forms as objects of knowledge.

J. Burnet claimed that Socrates gave a new meaning to ψνχή which is seen in the υεράπεια φυχής advocated in the Apology. Plato at first seems so involved in this conception of the soul as a moral agent that he tries to bend to its service both the conception of the soul as a life-principle with which all earlier speculation in physics and medicine had concerned itself and the Pythagorean or ‘Orphic’ story of the soul as a fallen δαίμων condemned to transmigration but able eventually to return to divine or demonic life. Naturally the three elements, physical, ‘Orphic’ and Socratic, will not lie down comfortably together; but Plato refuses to be daunted by this, and in his later dialogues, beginning from Phaedrus 245c and continuing through Timaeus, Philebus and Laws 10, he produces a doctrine of ψυχή as the source of change in nature and in human action-patterns alike: he sees the universe as an ensouled creature, and indeed, in the closing words of the Timaeus, as υεòς αϊσυητός, a divinity apprehended by the senses—though to become like this divinity ourselves we must make the moral decision to take intelligence into our lives and to reject mindlessness and destructive evil.

IN some ways it is regrettable that consideration of the Timaeus has been dominated in recent years by the controversy concerning its place in the sequence of Plato’s dialogues. Plato’s recognition of a duty to say what he could about the physical universe and to enter seriously into Greek enquiry περì φύσεως makes this dialogue, or rather Timaeus’ monologue, of outstanding significance—wherever the dialogue belongs in relation to the rest. Anyone approaching the subject should read first G. E. R. Lloyd’s article on ‘Plato as a Natural Scientist’ in JHS 88 (1968), 78–92. We have recently a contribution from Vlastos in Plato’s Universe (Oxford, 1975), a series of lectures given at the University of Washington, with annotations on various cruces of the dialogue.

The questions of divinity and of ultimate causation are not really separable in considering Plato. He did, of course, criticize prevailing conceptions of deity and showed himself, like Socrates in the Apology, as no atheist but a believer in the gods ‘in a way none of his accusers believed in them’ (35d). In his τύποì περὶϑεoλoγίaς in Republic 2 379a he challenges the legends and demands a reformed theology for educational purposes. There has been a tendency to ignore the more simply religious belief in a personal providential power which Plato seems to have inherited from Socrates (for one may at least trust Xenophon here as supporting evidence).

TO give this chapter this heading is to beg the whole question, for the champions of the Unwritten Doctrines as the essence of Plato’s philosophy maintain that a consciously formed and systematic approach to Being underlies all outward expressions in the dialogues and offers the key to all Plato’s thought. Such a view came to expression in the work of two German scholars, whose influence on their contemporaries was great and who, almost unwillingly, founded a kind of ‘school’ of Platonic philosophy. The most important work was that of Hans-Joachim Krämer, Arete bei Platon und Aristoteles (Heidelberg, 1959), supported by his Die Ursprung der Geistesmetaphysik (Amsterdam, 1964). The other really important book is Konrad Gaiser’s Platons Ungeschriebene Lehre (Stuttgart, 1963), which is rather less firmly dogmatic and an easier introduction to the questions at issue for those with German.