What is the theme in The Complete Plays by Aristophanes?

One of the central and recurring themes in the plays of Aristophanes is his opposition to Cleon and radical democracy. Aristophanes believed that Cleon and his manipulation of the Demos were at least partially responsible for the continuation of the ruinous war with Sparta. He believed that once the population had lost its moral and civic virtue, it was open to manipulation by crass demagogues like Cleon who would promise the average person petty power and wealth in exchange for votes. Aristophanes' savagely attacks Cleon in most of his plays and was apparently prosecuted by Cleon for treason for some of the accusation he made in his play, Babylonians.