Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
And if by perseverance of study he pass even beyond these gentler slopes, fruits for which none have toiled thrust themselves upon him, and all things spring forth unbidden; and yet if they be not gathered daily, they will wither away. But even such wealth must observe the mean, without which nothing is either praiseworthy or beneficial, while brilliance must be attended by manliness, and imagination by soundness of taste.
Thus the works of the orator will be great not extravagant, sublime not bombastic, bold not rash, severe but not gloomy, grave but not slow, rich but not luxuriant, pleasing but not effeminate, grand but not grandiose. It is the same with other qualities: the mean is safest, for the worst of all faults is to fly to extremes.
After employing these gifts of eloquence in the courts, in councils, in public assemblies and the debates of the senate, and, in a word, in the performance of all the duties of a good citizen, the orator will bring his activities to a close in a manner worthy of a blameless life spent in the pursuit of the noblest of professions. And he will do this, not because he can ever have enough of doing good,