“The safest general characterization of the European philosophical tradition”, wrote Alfred North Whitehead in Process and Reality, “is that it consists of a series of footnotes to Plato.”  If he is even partially or qualifiedly correct, we would be remiss not to make ourselves familiar with Plato’s writings.
Plato (420’s–348/347 B.C.) did not write treatises, but dialogues (letters aside). Plato himself does not directly show up in these dialogues — similar to how Shakespeare does not directly appear in his plays. Likewise, just as locating Shakespeare’s voice among the voices of his characters can be quite tricky, so too locating Plato’s voice is not always a simple affair.
Plato’s dialogues are customarily divided into three periods — his early, middle, and later dialogues. His early dialogues are understood to focus on Socrates as a moral philosopher, where ethical concerns predominate in response to what can rightly be called the moral relativism and skepticism of the Sophists. (To oversimplify: the Sophists were a phenomenon, rather than an organized group, like a church or a guild: the Sophists were rhetoricians, public speakers who would teach the art of persuasion-through-speech to clients willing to pay them. In Athens, where laws were passed –or vetoed– by speaking in the public assembly, this skill was a veritable means to power.) Plato’s middle dialogues also feature Socrates as the protagonist, although these middle dialogues are where we get the first flowering of Plato’s more mature thought, with a more robust and developed metaphysics and epistemology on display, among other things (the well-known Republic is among these middle dialogues). His later dialogues are not our concern here.
Plato’s dialogue the Phaedo is usually classed as the final of a trilogy of dialogues dealing with the trial and death of Socrates: the Euthyphro, the Apology, and then our dialogue, the Phaedo. The Euthyphro and the Apology are usually dated to Plato’s early period, but the Phaedo is dated to his middle period, and the more mature metaphysical concerns of his middle period are well on display in this dialogue.
There is one section of the Phaedo where Plato has Socrates recount Socrates’ own philosophical path, his own intellectual biography. It is fascinating, and some of us might be tempted to read it either as an intellectual biography either of Socrates or Plato. We must be careful.
In general, the Phaedo is better read as a philosophical memoir than as a biographical record. Even the famous passage in which Socrates rehearses the story of his intellectual development (96a–100a) [our excerpt, link below] is artfully contrived to serve a philosophical purpose, and may have little or no foundation in fact. 
There it is: you’ve been warned.
If you are considering digging into this passage, dear reader, there are numerous translations and secondary sources worth your attention. You can read a professional summary on this section of the Phaedo at the Internet Encyclopedia of Philosophy here; Eva Brann, of St. John’s Annapolis, has a written work on the Phaedo here; Alex Long has a translation here published by Cambridge that I own, but can’t find, so I can’t comment on at all; David Gallop has an excellent translation with commentary here (he has seemingly the same translation without this Clarendon commentary here, which is what I used below); the Greek edition (with English commentary) in Cambridge’s famous “green and yellow” series by Rowe is here; if you want to cut your teeth on the Greek, Steadman’s edition can be found here. There are chapters on our section of the Phaedo (and the section of the Phaedo following our section, continuing its line of thought) in G. Reale’s Toward a New Interpretation of Plato and Dancy’s Plato’s Introduction of Forms. If you don’t have the time to read, but do have the time to listen, I encourage you to give your ear to this audio dramatization.
In the PDF linked to below, the italicized numbers in brackets are approximations to the Stephanus numbers (and should give you a sense of how difficult it is to get precision in this from English translations), and the non-italicized numbers in brackets are the page numbers in the respective translations. To see the Stephanus edition of the Phaedo, click here.
It seems that I can’t embed a PDF or an MS Word file here, unfortunately, without doubling what I pay monthly (and I don’t want to recoup that expense by hitting you with ads). The link below has my three-column compilation of David Gallop’s translation [Plato, Phaedo, transl. David Gallop (New York: Oxford, 1993)] together with the translation of the Phaedo in the Cooper-Hutchinson volume [Plato, Complete Works, ed. John M. Cooper, Assoc. Ed. D. S. Hutchinson (New York: Hackett, 1997), 83 ff.], as well as an edition of the Greek original compiled from the Perseus.Tufts site. I didn’t look too carefully at the Greek, and I wasn’t always sober when I did, so I can’t promise that it always breaks evenly with the English translations.
There are several typos. Please do correct me on any infelicities in my compilation! I hope you find it useful. For those of you who don’t want to click on a link to download anything at all, here is the Gallop translation:
[Socrates:] [95b] […] The sum and substance of what you’re after is surely this: you want it proved that our soul
[95c] is imperishable and immortal, if a philosophic man about to die, confidently believing that after death he’ll fare  much better yonder than if he were ending a life lived differently, isn’t to be possessed of a senseless and foolish confidence. As for showing that the soul is something strong and god-like, and existed even before we were born as human beings, nothing prevents all that, you say, from indicating not immortality, but only that soul is long-lived and existed somewhere for an immense length of time in the past, and knew and did all kinds of things; even so,
[95d] it was none the more immortal for all that, but its very entry into a human body was the beginning of its perishing, like an illness: it lives this life in distress, and finally perishes in what is called death. And, you say, it makes no difference, so far as our individual fears are concerned, whether it enters a body once or many times: anyone who neither knows nor can give proof that it’s immortal should be afraid, unless he has no sense.
[95e] Something like that, Cebes, is what I think you’re saying; and I’m purposely reviewing it more than once, so that nothing may escape us, and so that you may add or take away anything you wish.
To this Cebes replied: ‘No, there’s nothing at present that I want to take away or add; those are my very points.’
Here Socrates paused for a long time examining some thing in his own mind. He then said:
‘It’s no trivial matter, this quest of yours, Cebes: it calls for a thorough inquiry [96a] into the whole question of the reason for coming-to-be and destruction. So I will, if you like, relate my own experiences on these matters: and then, if any of the things I say seem helpful to you, you can use them for conviction on the points you raise.’
‘Well, I certainly should like that,’ said Cebes.
‘Then listen to my story. When I was young, Cebes, I was remarkably keen on the kind of wisdom known as natural science; it seemed to me splendid to know the reasons for each thing, why each thing comes to be, why it perishes, [96b] and why it exists. And I was always shifting back and forth, examining, for a start, questions like these: is it, as some said, whenever the hot and the cold give rise to putrefaction, that living creatures develop? And is it blood  that we think with, or air, or fire? Or is it none of those, but the brain that provides the senses of hearing and seeing and smelling, from which memory and judgment come to be; and is it from memory and judgment, when they’re acquired stability, that knowledge comes to be accordingly?
[96c] Next, when I went on to examine the destruction of those things, and what happens in the heavens and the earth, I finally judged myself to have absolutely no gift for that kind of inquiry. I’ll tell you a good enough sign of this: there had been things that I previously did know for sure, at least as I myself and other thought; yet I was then so utterly blinded by this inquiry, that I unlearned even those things I formerly supposed I knew, including, amongst many other things, why it is that a human being grows. That, I [96d] used earlier to suppose, was obvious to everyone: it was because of eating and drinking;
whenever, from food, flesh came to accrue to flesh, and bone to bone, and similarly on the same principle the appropriate matter came to accrue to each of the other parts, it was then that the little bulk later came to be big; and in this way the small human being comes to be large. That was what I supposed then: reasonably enough, don’t you think?’
‘I do,’ said Cebes.
‘Well, consider these further cases: I used to suppose it was an adequate view, whenever a large person standing [96e] beside a small one appeared to be larger just by a head; similarly with two horses. And, to take cases even clearer than these, it seemed to me that ten was greater than eight because of the accruing of two to the latter, and that two cubits were larger than one cubit, because of their exceeding the latter by half.’
‘Well, what do you think about them now?’ said Cebes.
‘I can assure you that I’m far from supposing I know the reason for any of those things, when I don’t even accept from myself that when you add one to one, it’s either the one to which the addition is made that’s come to be two, or [97a] the one that’s been added and the one to which it’s been added, that have come to be two, because of the addition of one to the other. Because I wonder if, when they were apart  from each other, each was one and they weren’t two then; whereas when they came close to each other, this then became a reason for their coming to be two – the union in which they were juxtaposed. Nor again can I any longer be persuaded, if you divide one, that this has now become a reason for its coming to be two, namely division; because if [97b] so, we have a reason opposite to the previous one for its coming to be two; then it was their being brought close to each other and added, one to the other; whereas now it’s their being drawn apart, and separated each from the other.
Why, I can’t even persuade myself any longer that I know why it is that one comes to be; nor, in short, why anything else comes to be, or perishes, or exists, following that method of inquiry. Instead I rashly adopt a different method, a jumble of my own, and in no way incline towards the other.
‘One day, however, I heard someone reading from a book he said was by Anaxagoras, according to which it is, [97c] in fact, intelligence that orders and is the reason for everything. Now this was a reason that pleased me; it seemed to me, somehow, to be a good thing that intelligence should be the reason for everything. And I thought that, if that’s the case, then intelligence in ordering all things must order them and place each individual thing in the best way possible; so if anyone wanted to find out the reason why each thing comes to be or perishes or exists, [97d] this is what he must find out about it: how is it best for that thing to exist, or to act or be acted upon in any way? On this theory, then, a person should consider nothing else, whether in regard to himself or anything else, but the best, the highest good; though the same person must also know the worse, as they are objects of the same knowledge. Reckoning thus, I was pleased to think I’d found, in Anaxagoras, an instructor in the reason for things to suit my own intelligence. And I thought he’d inform me, first, [97e] whether the earth is flat or round, and when he’d informed me, he’d go on to expound the reason why it must be so, telling me what was better – better, that is, that it should be like this; and if he said it was in the centre, he’d go on to  expound the view that a central position for it was better. If [98a] he could make those things clear to me, I was prepared to hanker no more after any other kind of reason. What’s more, I was prepared to find out in just the same way about the sun, the moon, and the stars, about their relative velocity and turnings and the other things that happen to them, and how it’s better for each of them to act and be acted upon just as they are. Because I never supposed that, having said they were ordered by intelligence, he’d bring in any reason for them other than its being best for them to be [98b] just the way they are; and I supposed that in assigning the reason for each individual thing, and for things in general, he’d go on to expound what was best for the individual, and what was the common good for all; nor would I have sold those hopes for a large sum, but I made all haste to get hold of the books and read them as quickly as I could, so that I might know as quickly as possible what was best and what was worse.
‘Well, my friend, those marvelous hopes of mine were dashed; because, as I went on with my reading, I beheld a man making no use of his intelligence at all, nor finding in [98c] it any reasons for the ordering of things, but imputing them to such things as air and ether and water and many other absurdities. In fact, he seemed to me to be in exactly the position of someone who said that all Socrates’ actions were performed with his intelligence, and who then tried to give the reasons for each of my actions by saying, first, that the reason why I’m now sitting here is that my body consists of bones and sinews, and the bones are hard and separated from each other by joints, whereas the sinews, [98d] which can be tightened and relaxed, surround the bones, together with the flesh and the skin that holds them together; so that when the bones are turned in their sockets, the sinews by stretching and tensing enable me somehow to bend my limbs at this moment, and that’s the reason why I’m sitting here bent in this way;
or again, by mentioning other reasons of the same kind for my talking with you, imputing it to vocal sounds, air currents, auditory sensations, and countless other such things, yet  [98e] neglecting to mention the true reasons: that Athenians judged it better to condemn me, and therefore I in my turn have judged it better to sit here, and thought it more just to stay behind and submit to such penalty as they may ordain. [99a] Because, I dare swear, these sinews and bones would long since have been off in Megara or Boeotia, impelled by their judgment of what was best, had I not thought it more just and honorable not to escape and run away, but to submit to whatever penalty the city might impose. But to call such things “reasons” is quite absurd. It would be quite true to say that without possessing such things as bones and sinews, and whatever else I possess, I shouldn’t be able to do what I judged best; but to call those things the reasons [99b] for my actions, rather than my choice of what is best, and that too though I act with intelligence, would be a thoroughly loose way of talking. Fancy being unable to distinguish two different things: the reason proper, and that without which the reason could never be a reason! Yet it’s this latter that most people call a reason, appearing to me to be feeling it over blindfold, as it were, and applying a wrong name to it. That’s why one man makes the earth stay in position by means of the heaven, putting a whirl around it; while another presses down the air as a base, as if with a flat kneading-trough. Yet the power by which [99c] they’re now situated in the best way that they could be placed, this they neither look for nor credit with any supernatural strength; but they think they’ll one day discover an Atlas stronger and more immortal than that, who does more to hold everything together. That it’s the good or binding, that genuinely does bind and hold things together, they don’t believe at all. Now I should most gladly have become anyone’s pupil, to learn the truth about a reason of that sort; but since I was deprived of that, proving unable either to find it for myself or to learn it [99d] from anyone else, would you like me, Cebes, to give you a display of how I’ve conducted my second voyage in quest of the reason?’
‘Yes, I’d like that immensely,’ he said.
‘Well, then, it seemed to me next, since I’d been wearing  myself out studying things, that I must take care not to incur what happens to people who observe and examine the sun during an eclipse; some of them, you know, ruin [99e] their eyes, unless they examine its image in water or something of that sort. I had a similar thought: I was afraid I might be completely blinded in my soul, by looking at objects with my eyes and trying to lay hold of them with each of my senses. So I thought I should take refuge in theories, and study the truth of matters in them. Perhaps [100a] my comparison is, in a certain way, inept; as I don’t at all admit that one who examines things in theories is any more studying them in images than one who examines them in concrete. But anyhow, this was how I proceeded: positing on each occasion the theory I judge strongest, I put down as true whatever things seem to me to accord with it, both about a reason and about everything else; and whatever do not, I put down as not true. But I’d like to explain my meaning more clearly; because I don’t imagine you understand it as yet.’
‘Not entirely, I must say!’ said Cebes.
[100b] ‘Well, this is what I mean: it’s nothing new, but what I’ve spoken of incessantly in our earlier discussion as well as at other times. I’m going to set about displaying to you the kind of reason I’ve been dealing with; and I’ll go back to those much harped-on entities, and start from them, positing the existence of a beautiful, itself by itself, and of a good and a large and all the rest. If you grant me that and agree that those things exist, I hope that from them I shall display to you the reason, and find out that soul is immortal.’
[100c] ‘Well, you may certainly take that for granted,’ said Cebes, ‘so you couldn’t be too quick to conclude.’
‘Then consider the next point, and see if you think as I do. It seems to me that if anything else is beautiful besides the beautiful itself, it is beautiful for no reason at all other than that it participates in that beautiful; and the same goes for all of them. Do you assent to a reason of that kind?’
 ‘Then I no longer understand nor can I recognize those other clever reasons; but if anyone gives me as the reason why a given thing is beautiful either its having a blooming colour, or its shape, or something else like that, I dismiss those other things – because all those others confuse me – but in a plain, artless, and possibly simple-minded way, I hold this close to myself: nothing else makes it beautiful except that beautiful itself, whether by its presence or communion or whatever the manner and nature of the relation may be; as I don’t go so far as to affirm that, but only that it is by the beautiful that all beautiful things are beautiful. Because that seems to be the safest answer to give both to myself and to another, and if I hang on to that, I believe I’ll never fall: it’s safe to answer both to myself and to anyone else that it is by the beautiful that beautiful things are beautiful; or don’t you agree?’
If you are interested in more, please consult the above primary and secondary sources. I’ll likely comment on this passage more in the future.
Alfred North Whitehead, Process and Reality, Corrected Edition, ed. David Ray Griffin & Donald W. Sherburne (New York: The Free Press, 1978) 39
Plato, Phaedo, transl. David Gallop (New York: Oxford, 1993), x
Photo credit: apparently the cover of Setting Plato Straight: Translating Ancient Sexuality. I’ve not read the book, so I can neither recommend it nor trash it.