Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Never in my opinion would the founders of cities have induced their unsettled multitudes to form communities had they not moved them by the magic of their eloquence: never without the highest gifts of oratory
Nay, even the principles which should guide our life, however fair they may be by nature, yet have greater power to mould the mind to virtue, when the beauty of things is illumined by the splendour of eloquence. Wherefore, although the weapons of oratory may be used either for good or ill, it is unfair to regard that as an evil which can be employed for good.
These problems, however, may be left to those who hold that rhetoric is the power to persuade. If our definition of rhetoric as the science of speaking well implies that an orator must be a good man, there can be no doubt about its usefulness.