Aelian, Varia Hostoria II 13:

Anytus and his associates attacked and plotted against Socrates; their motives and reasons have been stated long ago. But they were suspicious of the Athenians, and fearful of how they would respond to the accusation against him. Socrates had made a great name for himself, in a variety of ways, including his refutation of the sophists, men of no merit, without any serious knowledge or claims to be heard. These men they decided to exploit as an experiment for their attack upon him. The idea of a direct charge against him in court without delay was rejected, both for the reasons I have already given and because of a fear that Socrates’ friends would be provoked into stirring up the jury against them and they might then suffer disaster, because they would have made malicious accusations against a man who not only had done no harm to the city but on the contrary was an ornament to Athens.

So what was their plan? They persuaded the comic poet Aristophanes, who was – and aimed to be – a vulgar and ridiculous humorist, to lampoon Socrates, making of course the well-known charges against him, that he was a windbag, that when he talked he would make the weaker argument seem superior, that he introduced foreign deities, was an atheist and did not honour the gods; that he taught his associates these same doctrines and persuaded them to believe accordingly. (1)

Aristophanes applied himself to the task with great energy, adding a little humour to it and some metrical versatility, and making the best man in Greece his theme. His play was not aimed at Cleon (2); it was not a satire on the Spartans, the Thebans, or Pericles himself, but on a man loved by the gods as a whole and especially by Apollo.

Since Socrates was an unusual subject, and odd figure on the stage in a comedy, the play at first astounded the Athenians by its unexpected theme. Later, as they had a natural tendency to jealousy and made a habit of criticising the best people, not only those in political life ands office-holders, but to an even greater degree men famous fort their literary accomplishments or honourable behavior, this play, The Clouds, was thought to be a very agreeable entertainment, and they applauded the poet. They shouted that he should win the prize, and they told the judges to put Aristophanes, and non one else, at the top of their list.

(1) Während „Die Wolken“ des Aristophanes 423 v.u.Z. aufgeführt wurden, hat der Prozeß gegen Sokrates mit den in Platons „Apologie“ 18a wiedergegebenen Anklagepunkten erst 399 stattgefunden.
(2) Kleon: attischer Demagoge der Zeit nach 430 v.u.Z.; Aristophanes hat ihn in „Die Ritter“ angegriffen.