In the Clouds we see a contest between philosophy and other claims to wisdom, in particular the claims of religion and poetry or the arts. There were great philosophers before Socrates, but they’re not concerned with politics. Rather they were concerned with nature, they investigated nature, and as such we can think of them as the contemporary equivalents of natural scientists. For them, politics was the place where conventions reigned, that is, there was no firm, no solid, no certain political knowledge to be discovered because everything was based upon mutual agreement.
Socrates is credited with bringing philosophy down into the streets from the heavens, with turning it from a concern with the stars to a concern with morals. In short, Socrates is credited with being the first to recognize the possibility that there may be a natural foundation underlying conventional things. Or put another way, Socrates is credited with recognizing that human beings live according to conventions by nature, that is, that conventions themselves are natural.