Many investigations regarding this were already made that the idea humanitas originated directly from Greek New comedy and especially from philosophy of Plato and the Stoics but fundamentally from the Greek literatures like those of Homer. Regarding to this, however, the real birth and growth place of the idea of humanitas and the sub-ideas was not classroom but forum in which legal court or political assembly was held. The most significant evidences for this are Cicero’s speeches, because it is not difficult to discover the fact that Cicero’s speeches are usually disposed according to the idea of humanitas and are full of sub-ideas of it. As an exmaple for this, I have tried to analyze Cicero’s Pro Roscio Amerino which is the first causa p...