The Ionians of Asia Minor had certainly identified the soul with that in us which is conscious, and which is the seat of goodness and badness, wisdom and folly; but they did not regard it as what we call the self or treat it as an individual. Anaximenes and his school held that the soul was what they called Air, but that was just because they regarded Air as the primary substance of which all things are made. The soul was something, in fact, that comes to us from outside (θυραθεν) by means of respiration. As Diogenes of Apollonia expresses it, it is ‘a small portion of the god’, that is, of the primary substance, enclosed in a human body for a time, and returning at death to the larger mass of the same substance outside. The formula ‘Earth to earth and air to air’ was accepted as an adequate description of what takes place at death. The western Ionians, and especially the Pythagoreans, held a very different view. For them, the soul was something divine. It was, in fact, a fallen god, imprisoned in the body as a punishment for antenatal sin, and it deserved our care in this sense, that it was our chief business in life to purify it so as to secure its release from the necessity of reincarnation in another body. But, during this present life, they held that this divine element slumbers, except in prophetic dreams. As Pindar puts it, ‘It sleeps when the limbs are active.’ Neither of these views was familiar to the ordinary Athenian, but Socrates of course knew both well, and felt satisfied with neither. When he spoke of the soul he did not mean any mysterious fallen god which was the temporary tenant of the body, but the conscious self which it lies with us to try to make wise and good. On the other hand, his insistence on our duty to ‘care for’ it is quite inconsistent with the view that it is merely something extrinsic, as all the eastern Ionians down to Anaxagoras had taught. It is, on the contrary, our very self, the thing in us which is of more importance to us than anything else whatever. It was to this doctrine of the soul and our duty to it that Socrates felt he must convert mankind and especially his fellow-citizens. It was a strange and novel doctrine then; and, if it has become a commonplace since, that only shows that he was successful, if not in persuading his fellowmen to act on this knowledge, at least in making them aware of it. It was in this way that Socrates healed the rift between science and religion which had proved fatal to the Pythagorean society, and it may be suggested that the significance of his teaching is not exhausted yet. As has been indicated above it is to be found clearly stated in Plato’s Apology of Socrates, and it furnishes the only clue to a right understanding of the great series of Platonic dialogues down to and including the Republic in which Socrates is represented as the chief speaker. Whether Plato added much or little of his own to the doctrine of his master in these dialogues is an interesting historical problem, but it need not concern the ordinary reader, at least in the first instance. We know from the allusions of Aristophanes that Socrates himself taught a new doctrine of the soul when Plato was a child, and no sympathetic reader can fail to see that the passage of the Apology to which we have referred is intended to be a faithful account of that doctrine. All the rest is simply its legitimate development, and it is not of very great importance for us to determine whether that development is due to Socrates or to Plato. The inspiration which has been derived from these writings by many generations will not be lessened by any decision we may come to on this point, so long as we keep clearly in mind that the new doctrine of soul is their principal theme, and that this must be understood in the light of the doctrines which had prepared the way for it. What Socrates did was really this. He deepened the meaning of the Eastern Ionian doctrine by informing it with some of the feeling and emotion which had characterized the Pythagorean teaching on the subject, while on the other hand he rationalized the Pythagorean theory by identifying the soul with our conscious personality.
Now if this is a correct account of what Socrates taught, he must be regarded as inaugurating an entirely new period in the history of philosophy. That is implied in the common term ‘Presocratics’ generally applied to his predecessors, though the ordinary textbooks are by no means clear as to the grounds for assigning this pre-eminent position to Socrates. We can also see how natural it was for him to lay such emphasis on the conversion of souls as he certainly did. That purpose continued to dominate Greek philosophy to the very end. No doubt successive schools varied in their conception of what conversion meant, but that is the link which binds them all together. In fact, it gave rise to a new literary form, the ‘hortatory discourse’ (προτρεπτικος λογος), which was more and more cultivated as time went on, and was at last taken over by the fathers of the Christian church along with much else of a more fundamental character.
It has been noted already that Socrates had followers among all the leading philosophical schools of the time, and the possibility is not to be excluded that we may still learn more of him from the discovery of new sources. For the present, the recovery of some new and fairly extensive fragments of the Alcibiades of Aeschines of Sphettos is the chief addition to our sources of information. We know that Aeschines was a disciple of Socrates, and the tradition of antiquity was that his dialogues gave the most faithful picture of the man as he really was. If so, that was probably because Aeschines had no philosophy of his own. For us the chief importance of the new fragments is that, if we read them along with those already known (and it is unfortunate that the old and the new have not yet been printed together), they strongly confirm the impression we get from Plato of the manner of Socrates and his method of argument, and that helps to reassure us as to the essentially historical character of the Platonic Socrates. The fragments of Aeschines also corroborate Plato by showing that the conversion of Alcibiades (whose life he had saved when a young man) was one of the things that lay nearest his heart.
But the real successor of Socrates was, of course, Plato himself (427–347 BC). It is not possible to give even an outline of Plato’s philosophy here. Indeed the time has hardly come for that yet, though much admirable work is now being done, especially by a French professor, M. Robin, which promises more certain conclusions than have yet been possible. All that can be attempted here is to indicate the attitude of Plato to some of the problems we have been discussing. His very great contributions to the theory of knowledge will be passed over, as they are beginning to be well understood, and the Theaetetus in particular, with its sequel the Sophist, is more and more coming to occupy its rightful place as the best introduction to philosophy in general. It is necessary, however, just to notice in passing a fundamental question of method which the Platonic dialogues themselves suggest. It is this. While Socrates is present in every one of them except the Laws, he takes practically no part in some of them, and the dialogues in which this is the case are known on other grounds to belong to the later years of Plato’s life. There must be some reason for this, and it is obviously prudent to treat these later dialogues in the first instance as our primary evidence for Plato’s own views. Indeed, it is only after his philosophy has been reconstructed