In Ancient Greece, public speaking was the main channel for political debate and decision-making, legal decision-making, and even philosophical discussion.
As it became more and more important to society, so did rhetoric, which is the art of persuasive speaking and writing. Ancient philosophers like Plato, Aristotle, and Cicero studied and practiced rhetoric… essentially boiling it down to a do-it-yourself guide.
That guide has been lost (ok, just forgotten). Until now.