Socrates begins his speech by distinguishing between truth and persuasion. He, Socrates, speaks the truth in a plain way, while his accusers speak falsehoods in an eloquent way. This reflects Socrates' continuing battle with the Sophists, who taught their students (for a large fee) how to speak persuasively regardless of the truth of what they were saying. It also illustrates Socrates' famous use of irony.
Next he distinguishes between his present accusers (who claimed that he corrupted the youth of Athens by turning them against religion) and his long-time accusers, who accuse him of being a wise man who studies things beyond the earth, and is able to "make the worse argument stronger." The latter accusers will be addressed first, since their charges have become deeply ingrained. Socrates had been accused of making claims to knowledge of the supernatural ("saying he was walking on air"), but this is false, as many people know.
What was the origin of the false charges against Socrates? They center around Socrates' wisdom. The oracle at Delphi (a kind of prophet) had said that no man is wiser than Socrates. Yet upon pondering this answer, Socrates was perplexed, since he had thought that he was not wise at all, yet the oracle does not lie. Undertaking to find someone wiser than himself, Socrates sought out men with the reputation for wisdom and found them to be unwise. He proved it to them, thus incurring their displeasure. Further, he discovered that there is an inverse relation between reputation and wisdom: those reputed to most wise were least so, and vice versa. The politicians knew practically nothing, while the poets at least had some inspiration, though not knowledge. The crasftsmen had knowledge of their crafts but claimed knowledge of other things.
The result of the investigation was that Socrates concluded that what the oracle meant is the human wisdom is worthless, and at least he, Socrates, understood that. By exposing the pretensions of those who believed themselves wise, Socrates was doing service for the oracle.
The specific charge that Socrates corrupted the youth of Athens is now explained: young followers of Socrates imitated his method and exposed other people as unwise. The accusers have no explanation of how Socrates does it, other than vague charges leveled at all philosophers: that they dabble in the supernatural, that they deny the existence of the gods, and that they make weaker arguments appear stonger.
Now Socrates confronts his accuser, Meletus. He charges him with being irresponsible in bringing his charges, in that he does not really care about the issues in question. First, Socrates gets Meletus to admit that bad people do harm to those around them, so that if Socrates is corrupting youth, he is endangering himself. But he is not so ignorant as to do this deliberately, so either he does not corrupt the youth at all, or else he does not do so willingly. In neither case should charges be brought against him.
The charge of atheism is taken up next. Meletus repeats his accusation that Socrates believes in no gods at all, yet Socrates gets him to admit that anyone who engages in divine activities must believe in a god, and that he, Socrates, engages in divine activities. Socrates held that he was carring out the divine will (which he later says he first heard as a child) in living the philosophical life.
Someone in divine service should not fear death, and indeed, fear of death is another indication of pretended wisdom, since it is based on the assumption that death is bad for us, while we are ignorant of the matter. Although Socrates claims no knowledge of the underworld (the place of life after death), he does know "that it is wicked and shameful to do wrong, to disobey one's superior, either god or man." Socrates' mission is to teach that each person should achieve the best possible state of the soul. It is excellence of the soul which leads to wealth and other material goods, rather than vice-versa.
Socrates turns the tables on the proceedings, claiming not to be arguing on his own behalf, but on behalf of the jury. He claims that he cannot be harmed by his accusers, since the soul of a better man cannot be harmed by the acts of the worse. But the jury can bring harm on themselves by condeming the man who is carrying out a useful mission from the gods. There would be no one left to puncture their pretensions.
The mission in a way is unnatural, as Socrates has neglected all ordinary affairs, without profit to himself, to persuade the Athenians to care for virtue. And this life must be private, for anyone arguing for justice in the official forum would not survive very long. A case in point is a time when Socrates was the rightful dissenter in a case which saw six men executed, and the majority of the jury wanted to prosecute him. Another was when he refused to obey an unjust order; he would have been executed had the government not fallen. But Socrates was never concerned with death, but only not to do anything unjust or impious.
Socrates claims not to have been a teacher, and his discussions never depended on money. He allowed anyone to partake in his discussions, and he questioned anyone -- rich or poor. People like to see the pretentious cut down to size, but Socrates does it only because he thinks he is divinely inspired to do so. And none of those he allegedly "corrupted" or any of their relatives have made any charge against him.
The speech ends with Socrates' explanation of his refusal to beg for mercy: it is shameful to do so. Instead, he seeks to teach and persuade the jury, so that they may uphold the law.
After the guilty verdict has been delivered and Meletus has asked for the death penalty, Socrates discusses his counter-proposal. His irony shows through again: since he has benefitted people more than Olympic champions, he should get free meals at the place of celebration. The point is that if he proposed some lesser sentence than death for himself, he would be recommending that some evil be done to him. He does not want to be imprisioned, and he has no money for a fine. As for exile, he would met the same fate in another city, being driven out again, because he cannot be quiet. In the end, Socrates proposes a fine, to be made good by Plato and some others.
The jury sentences Socrates to death, however. Now Socrates admonishes them that they will bring shame upon themselves for doing what they are about to do, killing a man widely thought to be wise. He would have died soon anyway, given his advanced age of 70. Socrates states that he was convicted because he refused to humble himself before the jury. "I would much rather die after this kind of defence than live after making the other kind." Death is not hard to avoid, if one is shameless enough, but wickedness is. The jury through its actions has condemned itself to wickedness and injustice.
Socrates prophesizes that the jury will have created even more of a problem by eliminating Socrates. His followers, who have been held back, will hound them; and they are more numerous and vigorous than Socrates himself. One cannot escape reproach for failing to live a good life. "To escape such tests is neither possible nor good, but it is best and easiest not to discredit others but to prepare oneself to be as good as possible."
A further reason Socrates is convinced he has done the right thing is that his divine sign has not opposed any action in his defense, though it has opposed him many times before. Socrates takes that to indicate that death is a good thing for him. There is also a rational argument to this conclusion: either death is unconsciousness or it is a passage to another life. A dreamless sleep is a blessing, as we know from experience. If it is a passage to another life, so much the better. One would be judged by upright judges and enjoy the company of the dead sages. Moreover, Socrates could continue to carry out his task of testing the apparently wise.
A good man cannot be harmed in life or in death. What has happened to Socrates apparently was meant to happen. But the blameworthy judges should be avenged by Socrates' offspring by hounding those who care for money more than virtue, or are falsely puffed up. "Reproach them as I reproach you, that they do not care for the right things and think they are worthy when they are not worthy of anything."