You can read Meno online in English at the Perseus Project or in French at Wikisource.
(in order of appearance)
A handsome and wealthy youth from the Athenian ally Thessaly, who has been doing some studying under Gorgias. Meno will become a general who will participate in the expedition of the Persian prince Cyrus (in which Xenophon also participated); in his first mission, which is to escort an ally, he will manage somehow to lose a hundred men and plunder a peaceful city. He would eventually be tortured to death (or more accurately, tortured in prison for a year before being tortured to death), and Xenophon, who, while not above being firmly partisan or harsh in his judgment, is not cruel, clearly thinks that he deserved it. Xenophon's rant against him in Anabasis is just truly remarkable; sober, calm, level-headed Xenophon despised the man. I just have to put it here in full, because it is all worth reading (Anabasis 2.6.21-27):
Menon the Thessalian was manifestly eager for enormous wealth — eager for command in order to get more wealth and eager for honour in order to increase his gains; and he desired to be a friend to the men who possessed greatest power in order that he might commit unjust deeds without suffering the penalty. Again, for the accomplishment of the objects upon which his heart was set, he imagined that the shortest route was by way of perjury and falsehood and deception, while he counted straightforwardness and truth the same thing as folly. Affection he clearly felt for nobody, and if he said that he was a friend to anyone, it would become plain that this man was the one he was plotting against. He would never ridicule an enemy, but he always gave the impression in conversation of ridiculing all his associates. Neither would he devise schemes against his enemies' property, for he saw difficulty in getting hold of the possessions of people who were on their guard; but he thought he was the only one who knew that it was easiest to get hold of the property of friends—just because it was unguarded. Again, all whom he found to be perjurers and wrongdoers he would fear, regarding them as well armed, while those who were pious and practised truth he would try to make use of, regarding them as weaklings. And just as a man prides himself upon piety, truthfulness, and justice, so Menon prided himself upon ability to deceive, the fabrication of lies, and the mocking of friends; but the man who was not a rascal he always thought of as belonging to the uneducated. Again, if he were attempting to be first in the friendship of anybody, he thought that slandering those who were already first was the proper way of gaining this end. s for making his soldiers obedient, he managed that by bearing a share in their wrongdoing. He expected, indeed, to gain honour and attention by showing that he had the ability and would have the readiness to do the most wrongs; and he set it down as a kindness, whenever anyone broke off with him, that he had not, while still on terms with such a one, destroyed him.
There's an obituary for you! Xenophon does go on to say that one might be mistaken about him in matters that aren't known to everyone; that is, this assessment is what Xenophon thinks you get of him if you just focus on a just and fair assessment of the facts that gives him the benefit of the doubt! It should be said, though, that nobody else comes out quite this strongly against Meno; and that Xenophon explicitly says that he knows of the circumstances of Meno's death only by report. But it's an interesting exercise to read Meno, then read Xenophon's description of him, and then read Meno again.
Anytus son of Anthemion
The presence of Anytus in the dialogue directly shows that there is much more going on here than might at first be obvious, because Anytus is one of the people who would later bring charges against Socrates to have him put to death. Anytus was a wealthy man who had inherited a tannery; he was active in politics. Something of his political approach is known from the fact that he was once prosecuted for misconduct as a general and he got off by bribing the jury. Because he was a partisan of the democratic factions, he was banished by the Thirty Tyrants despite being an associate of one of them (Theramenes), but when the oligarchy was overthrown and democracy restored, he became one of the major leaders of the new democratic government. He (along with Meletus) brought charges against Socrates, thus leading to his death. An old tradition, found in Diogenes Laertius, says that he was lynched when the Athenians began to regret what had happened with Socrates -- but other evidence suggests that he lived happily ever after
In addition there is an anonymous slave of Meno.
The Plot and the Thought
Meno opens the dialogue by asking Socrates whether virtue can be taught, or whether it is the result of practice, or whether it is had by nature. Socrates remarks that while Thessalians are noted for wealth and horsemanship, through the work of Gorgias they have become wise, since they, like he, have come to give bold answers to big questions; but in Athens things don't work that way. He then says that since he does not know what virtue is, he cannot say what its features are, nor does he know anyone who does. Meno is surprised because Socrates has met Gorgias, and Socrates responds ironically that he doesn't remember what Gorgias's view was, but he's willing to discover what Meno thinks it is.
Meno gives a little speech describing different kinds of virtue and Socrates ironically responds that he is very fortunate to be talking to Meno, since he looked for one virtue and found swarms. So he asks Meno about bees, and the implications of saying what bees are by telling people that they are varied and many and of different kinds; people would still need to know what makes all of them bees. So likewise, one needs to know what makes all these different virtues to be virtues. Through a series of questions Socrates presses Meno to accept that all the virtues he mentioned require temperance (sophrosyne) and justice (dikaiosyne). But we run into the same question: are these virtue, or are these particular virtues? Socrates then uses the analogy of shape, and then that of color, to try to convey what he is looking for.
Meno then claims that "virtue is to desire beautiful things and have the power to acquire them" (77b). Socrates notes that this is to say that virtue is the securing of good things -- but surely we have to add the qualification, 'justly and temperately'. So we are back to virtues when we want to know virtue. So what is virtue?
Meno is getting a bit annoyed at this point:
Socrates, before I even met you I used to hear that you are always in a state of perplexity and that you bring others to the same state and now I think you are bewitching and beguiling me, simply putting me under a spell, so that I am quite perplexed. Indeed, if a joke is in order, you seem, in appearance and in every other way, to be like the broad torpedo fish, for it too makes anyone who comes close and touches it feel numb, and my tongue are numb, and I have no answer to give you. (80a-b)
I find it hilarious, by the way, that Meno says Socrates looks like a torpedo fish, because this is what a torpedo fish looks like:
Meno ends on a more ominous note, however: "I think you are wise not to sail away from Athens to go and stay elsewhere, for if you were to behave like this as a stranger in another city, you would be driven away for practising sorcery" (80b).
Socrates remarks that the torpedo fish metaphor is only accurate if torpedo fish don't just numb others but numb themselves, because he himself does not claim to avoid perplexity about what virtue is.
This brings us to the most famous part of the dialogue, as Meno asks how Socrates can search for virtue if he does not know what it is. Thus we have Meno's Paradox: If you know what you're looking for, you've already found it, and if you don't know what you're looking for, you cannot recognize it when you do find it. But Socrates argues that this is not right, and introduces a myth of recollection:
As the soul is immortal, has been born often and has seen all things here and in the underworld, there is nothing which it has not learned, so it is in no way surprising that it can recollect the things it knew before, both about virtue and other things. As the whole of nature is akin, and the soul has learned everything, nothing prevents a man, after recalling one thing only -- a process men call learning -- discovering everything else for himself, if he is brave, and does not tire of the search, for searching and learning are, as a whole, recollection. We must, therefore, not believe that debater's argument, for it would make us idle, and fainthearted men like to hear it, whereas my argument makes them energetic and keen on the search. (81c-d)
Meno asks what this means, so Socrates has him call in a Greek-speaking slave. By questioning he then leads the slave through a geometry problem. Socrates uses this to argue that the slave in some way had the opinions in him already, and by questioning were "stirred up like a dream" (85c); if one continued questioning, asking about the same thing in different ways, the slave could be said to know it as well as anyone. Thus knowledge seems to be a recollection from a prior life, when one was not human, and we should strive boldly to recollect:
I do not insist that my argument is right in all other respects, but I would contend at all costs both in word and deed as far as I could that we will be better men, braver and less idle, if we believe that one must search for the things one does not know, rather than if we believe it it snot possible to find out what we do not know and that we must not look for it. (86b-c)
Therefore, Socrates concludes, he and Meno should work together to discover what virtue is. But Meno replies that he would be happiest if they could investigate the original question: whether virtue is teachable, or natural, or what have you. Socrates remarks that if he were directing Meno, they would not investigate that question until they knew what virtue was; but, he says, "because you do not even attempt to rule yourself, in order that you may be free, but you try to rule me" (86d), he will go along with it. But he suggests that they proceed by a method of supposition or hypothesis, using an example from geometry again to clarify what he means.
So begins an argument considering the question on supposition that virtue is knowledge. If virtue is knowledge it seems to be teachable. So is there reason to think that the supposition is true or false? Virtue makes us good and thus is beneficial; but all the qualities we call virtue are only beneficial when combined with wisdom or prudence (phronesis). Thus it seems that virtue is a kind of prudence. If this is so, though, this appears to rule out the idea that virtue is had by nature, and it seems virtue can be taught.
But perhaps virtue is not knowledge at all. If virtue is teachable, we should be able to find teachers of virtue, and Socrates remarks that despite trying hard to do so, he's never been able to find any. He remarks that Anytus has come to sit by them, so suggests they make use of his wisdom to find out who are the teachers of virtue.
In dialogue with Anytus, Socrates remarks that it seems that if Meno wishes to learn virtue, he should go to the sophists, who claim to teach it. Anytus, not a fan of the sophists, replies that instead they cause ruin and corruption. Socrates remarks that it's strange that they would be able to get away with their claims to teach virtue if that were true, and asks if any sophist has wronged Anytus, and Anytus replies that he's never even met one. Socrates expresses surprise that he knows so much about people he's never met, and Anytus says he knows who they are even if he hasn't. Socrates skeptically remarks that Anytus must be a wizard, but asks Anytus who the teachers of virtue really are. Anytus replies that practically any Athenian he could meet would be a teacher of virtue, and they learned it from the good Athenians before them.
In response, Socrates raises the example of Themistocles, the great statesman of Athens, and Anytus agrees that he would be a good teacher of virtue. But even Anytus cannot admit that he definitely taught his son to excel in the same way he did. And so it is with other great men, like Aristides or Pericles, or Pericles' opponent, Thucydides. So it seems virtue cannot be taught.
Anytus is angry at this point, and says ominously:
I think, Socrates, that you easily speak ill of people. I would advice you, if you will listen to me, to be careful. Perhaps also in another city, and certainly here, it is easier to injure people than to benefit them. I think you know that yourself.(94e)
Socrates more or less brushes this off and returns to discussion with Meno, asking whether there are teachers of virtue among the sophists, and Meno says sometimes he thinks there are and sometimes not. But this in itself suggests that they are not. So there seem to be no teachers, and virtue cannot be taught.
But perhaps things were assumed too quickly here. True opinion can have the same results as knowledge. This leads Meno to wonder why knowledge is considered more important than true opinion. In response, Socrates compares them to the statues of Daedelus, which can run away; a statue of Daedelus that is not tied down is like a runaway slave, but a statue of Daedelus tied down is very valuable. Likewise, true opinions must be tied down by an account, and this tying-down is recollection.
So perhaps Themistocles and the like had no knowledge or prudence, but only true opinion about certain things -- they accomplish what they accomplish by a kind of divine inspiration. Meno concedes that this seems to be so. Thus the conclusion seems to be that virtue is "neither an inborn quality nor taught, but comes to those who possess it as a gift from the gods which is not accompanied by understanding" (99e).
Socrates then ends the dialogue with a comment pregnant with meaning:
It follows from this reasoning, Meno, that virtue appears to be present in those of us who may possess it as a gift from the gods. We shall have clear knowledge of this when, before we investigate how it comes to be present in men, we first try to find out what virtue in itself is. But now time has come for me to go. You convince your guest friend Anytus here of these very things of which you have yourself been convinced, in order that he may be more amenable. If you succeed, you will also confer a benefit upon the Athenians. (100b)
Quotations are from G. M. A. Grube's translation in Plato, Complete Works, Cooper & Hutchinson, eds., pp. 870-897.