Socrates remarks that Meletus, Anytus, and Lycon, who have brought the present charges before the court, are only the most recent of a number of people who have spoken out against him. He has more reason to fear his older accusers than these recent ones, because the former have been speaking out against him for some time, prejudicing many of the jurymen against him from the time of their youth. These older accusers levy two principal accusations against Socrates: first, that he does not believe in the gods, but rather teaches purely physical explanations for heavenly and earthly phenomena; and second, that he teaches how to make a weaker argument overcome a stronger argument by means of clever rhetoric. Socrates complains that he is not even certain who these older accusers are, though he makes a passing allusion to Aristophanes (the comic playwright who parodied Socrates in The Clouds). As a result, he cannot cross-examine these accusers, and he must acknowledge that the prejudices they have lodged against him go very deep. All he can do is answer their accusations as best as he can.
Socrates first addresses himself to the accusation that he "inquires into things below the earth and in the sky" (19b)--that is, that he tries to provide physical explanations for matters that are normally considered to be the workings of the gods. He refers here to Aristophanes' play, where Socrates is portrayed as floating about in the air and uttering all sorts of nonsense about divine matters. Socrates responds that he does not pretend to have any knowledge of these things, nor is he interested in them. He has no complaints against people who do claim to be experts in these affairs, but he is not one of them. He asks the jury to consider whether any of them has ever heard him speak about any of these subjects.
Socrates then distances himself from the sophists (the men who are typically disdained for teaching their students how to make weaker arguments overcome stronger arguments). These men generally charge a fee for their services, and Socrates denies ever having charged anyone for engaging in conversation with him. He ridicules such behavior, saying that a sophist will persuade young men "to leave the company of their fellow citizens, with any of whom they can associate for nothing, attach themselves to him, pay money for the privilege, and be grateful into the bargain" (19e-20a). These sophists claim to teach their students about virtue and how to become better citizens, and Socrates concedes that such teaching may well be worth a great fee, but that he himself lacks any skill in teaching these matters.
The main thrust of this section is to distance Socrates from the Presocratic philosophers and from the sophists, distinguishing him as unique among the Athenian intellectuals. The claim that Socrates provides physical explanations for divine phenomena is true of the Presocratics, and the claim that Socrates charges a fee for teaching rhetoric is true of the sophists, but neither claim is true of Socrates himself. He consistently professes to have no expertise in any field whatsoever; that he has never claimed such expertise; and that he has certainly never charged a fee for passing on such knowledge.
"Presocratic" philosophy refers to Greek philosophy untouched by Socrates' influence. The Presocratics date back to the sixth century B.C., when thinkers began to question the existing mythological explanations for the existence of the world, the universe, and matter, and began looking for physical explanations instead. Among the famous Presocratics are Thales, Pythagoras, Heraclitus, and Parmenides. The state sanctioned devout worship of the Olympian gods, so the Presocratics' teaching was considered illegal and dangerous. In the Phaedo (96a-98b), Socrates claims that in his youth, he was attracted to the teachings of Anaxagoras, one of the great Presocratics, but that he later abandoned that line of thinking. However, Socrates himself never taught such matters, and his defense at 19d is not that he was never interested in Presocratic philosophy, but that he never claimed expertise or taught it himself. Indeed, Socrates' teachings remained exclusively in the human realm, dealing with questions of ethics and virtue. One of his great contributions to philosophy is the introduction of ethical questions, and his dismissal of the Presocratic interest in cosmology.
The sophists were discussed in the previous section as men who trained Athenian youths for a career in politics by teaching them how to make convincing arguments and flowery speeches. Plato is determined to set Socrates apart from such men, and many of his dialogues have Socrates showing up the emptiness of their teachings. One of the great differences between Socrates and the sophists is that the sophists charged a fee for their services, and Socrates' poverty speaks to the fact that he has clearly not profited greatly from teaching.
As was mentioned earlier, one great source of these prejudices against Socrates comes from Aristophanes' The Clouds, in which Socrates is portrayed as an eccentric old fool who floats about suspended from a crane, spouting all sorts of nonsense about the heavens and the earth. Aristophanes also characterizes Socrates as charging a fee for his services. The Clouds was written in 423 B.C., 24 years before this trial, so whether it is the source of these prejudices or a reflection of even older prejudices, we can see that accusations against Socrates date from long before the trial.
Socrates' confession that he lacks any kind of expertise in any field whatsoever is central to his philosophy, and sets him apart from both the sophists and the Presocratics. Teachers from these two groups both claimed that through experience, inspiration, or investigation, they had gained access to special knowledge that could be taught. Socrates, on the other hand, never makes any particular claims to knowledge, and his inquiries tend to show the ignorance of his interlocutors rather than his own expertise. Socrates, then, has no particular knowledge, as such, to teach at all, but has instead a peculiar kind of wisdom that will be clarified in the sections following.
This is arguably one of Socrates' most famous quotes, and in fact, living the examined life was the main cause of him sippin' on a killer cocktail. But, what does he mean? Why does he think that death is favorable option to living an unexamined life? What does the examined (or conversely, the unexamined) life look like? Another way to think about this is "Why does Socrates so willingly accept his fate?". Just food for thought.