The Phaedo is the scene of the death of Socrates. Finally the ship from Delos has arrived and it is time for Socrates to drink the hemlock. At this point, with his friends about him, he discussed the interrelated problems of the soul and of knowledge. For the Greeks knowledge could only be of what could not be different from what it is. Thus knowledge can be only of unchanging things. Hericlitus, on the other hand, showed that everything is constantly changing. Thus Plato was forced to face what Aristotle called his "Hericlitean problem", that is how can we have knowledge of anything when everything is constantly changing. Yet we cannot deny Hericlitus' pronunciation in spite of the fact that we deal with it every day. Suppose for example that you were a close friend of John Smith when you both were young and then lose contact for a few decades. When you meet again he is still John Smith yet he has changed drastically. How can you say that you have knowledge of him? But if knowledge is only of the unchanging, then it is an Eleatic as well as a Hericlitean problem because it relegates all of those things that we deal with in our normal lives to the unreal. Hericlitus' solution, that the logos, what is constant beneath the changing things of our sensual existence tells us little or nothing and Parmenides solution that it is simply unreal is equally mysterious, for we must and do interact with these things that are under constant flux. Knowledge, in the Greek sense of what is unchanging, must then be eternal and what is eternal is divine. This means that if a man is to have knowledge, there must be a part of him that is divine. For Plato this was the soul. And at the same time, though we may deny reality to those things that are in constant flux, we must still deal with them in our everyday life. Plato's solution to this problem was the concept of participation. But he explains this much better than I in the Phaedo. The questions he asked to bring these ideas out dealt with the existence of such things as absolute justice, or absolute beauty. "Did you ever behold any of them with your eyes?" he asked. Or did you ever reach them with any other bodily sense?―and I speak not of these alone, but of absolute greatness, and health, and strength, and of the essence or true nature of everything. Has the reality of them ever been perceived by you through the bodily organs? or rather, is not the nearest approach to knowledge of their several natures made by him who so orders his intellectual vision as to have the most exact conception of the essence of each thing which he considers? In a world that is rational yet is filled with the irrational, the irrational must have a different kind of being. Reality in a rational world is quintessentially understandable, it can by definition become known. But the changing, the irrational, the unexpected, the world of the passions and the senses cannot be real. For if it was then the world would not be knowable, it would not be rational. Since it is the mind and the mind alone that can recognize the rational that lies behind the unreal sensual world, it is only through the mind that man can know the real world. And he attains to the purest knowledge of them who goes to each with the mind alone, not introducing or intruding in the act of thought sight or any other sense together with reason, but with the very light of the mind in her own clearness searches into the very truth of each; he who has got rid, as far as he can, of eyes and ears and, so to speak, of the whole body, these being in his opinion distracting elements which when they infect the soul hinder her from acquiring truth and knowledge―who, if not he, is likely to attain to the knowledge of true being? But there is a path to such knowledge. That is the path of philosophy. The path of the search for true wisdom requires a discipline which will avoid completely all of the evils brought on by the body. And when real philosophers consider all these things, will they not be led to make a reflection which they will express in words like the following? 'Have we not found,' they will say, 'a path of thought which seems to bring us and our argument to the conclusion, that while we are in the body, and while the soul is infected with the evils of the body, our desire will not be satisfied? And our desire is of the truth. For the body is the source of endless trouble to us by reason of the mere requirement of food; and is liable also to diseases which overtake and impede us in the search after true being: it fills us full of loves, and lusts, and fears, and fancies of all kinds, and endless foolery, and in fact, as men say, takes away from us the power of thinking at all. The body is part of the unreal world of the changing, the illusive. Knowledge must be of the unchanging, the divine. As such it can only be apprehended by the mind which alone can touch the divine through the faculty of reasoning. To be quit of the body means to have the fetters removed from the mind. It has been proved to us by experience that if we would have pure knowledge of anything we must be quit of the body―the soul in herself must behold things in themselves: and then we shall attain the wisdom which we desire, and of which we say that we are lovers; not while we live, but after death; for if while in company with the body, the soul cannot have pure knowledge, one of two things follows―either knowledge is not to be attained at all, or, if at all, after death. For then, and not till then, the soul will be parted from the body and exist in herself alone. In this present life, I reckon that we make the nearest approach to knowledge when we have the least possible intercourse or communion with the body, and are not surfeited with the bodily nature, but keep ourselves pure until the hour when God himself is pleased to release us. And thus having got rid of the foolishness of the body we shall be pure and hold converse with the pure, and know of ourselves the clear light everywhere, which is no other than the light of truth.' For the impure are not permitted to approach the pure. These are the sort of words, Simmias, which the true lovers of knowledge cannot help saying to one another and thinking. The idea of transmigration of souls dates back to Orphic and Pythagorean doctrine. Is that ancient belief enough? Not for Socrates. There must be some proof other than the beliefs of the ancients. As a philosopher he must have some reasoned argument that the souls of men are immortal and that after death they are reborn into a another body. Some argument that can be known through reason alone. Suppose we consider the question whether the souls of men after death are or are not in the world below. There comes into my mind an ancient doctrine which affirms that they go from hence into the other world, and returning hither, are born again from the dead. Now if it be true that the living come from the dead, then our souls must exist in the other world, for if not, how could they have been born again? And this would be conclusive, if there were any real evidence that the living are only born from the dead; but if this is not so, then other arguments will have to be adduced. Remember that by real arguments he means arguments that can be settled through reasoning. In our discussion of the presocratics, that in order for all things to change from one to another there had to be both an underlying substrata out of which everything came to be. There also had to be a source of eternal motion through which the interplay of opposites could occur which would result in the sensual world which we experience. This was the fundamental cause of existence for Heraclitus, Anaximander, Anaximenes, indeed most of the presocratic philosophers. The engine of change within the underlying substrata for all of them was the conflict of opposites in the eternally moving chaos. Then let us consider the whole question, not in relation to man only, but in relation to animals generally, and to plants, and to everything of which there is generation, and the proof will be easier. Are not all things which have opposites generated out of their opposites? I mean such things as good and evil, just and unjust―and there are innumerable other opposites which are generated out of opposites. And I want to show that in all opposites there is of necessity a similar alternation; I mean to say, for example, that anything which becomes greater must becomes greater after being less. And that which becomes less must have been once greater and then have become less. And the weaker is generated from the stronger, and the swifter from the slower. We need not go into detail concerning this exercise in Hericlitean doctrine to realize where Socrates is headed, that life and death are opposites and that one is generated from the other. And, if the living are generated from the dead then souls must exist in the world below. Of the two processes or generations one is visible--for the act of dying is visible. What, then, is to be the result? Shall we exclude the opposite process? and shall we suppose nature to walk on one leg only? Must we not rather assign to death some corresponding process of generation?" And what process would that be? why, return to life. This argument, as you can see, relates only to necessary logical connections between things that cannot not be. So he went on. And return to life, if there be such a thing, is the birth of the dead into world of the living. Then here is a new way by which we arrive at the conclusion that the living come from the dead, just as the dead come from the living; and this, if true, affords a most certain proof that the souls of the dead exist in some place out of which they come again. He thus offered further proof to back up these claims. This proof is particularly meaningful when we think, as the Greeks did, that the world is eternal and has always been just as it is. "If generation were in a straight line only, and there were no compensation or circle in nature, no turn or return of elements into their opposites, then it is obvious that all things would in time have the same form and pass into the same state, and there would be no more generation of them." If there were no alternation of sleep and waking, all things would be asleep. If there were composition only, and no division of substances, then the chaos of Anaxagorus would come again. "If all things which partook of life were to die, and after they were dead remained in the form of death, and did not come to life again, all would at last die, and nothing would be alive--what other result could there be? For if the living spring from any other things, and they too die, must not all things at last be swallowed up in death?"