Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Thus the purpose for which oratory was above all designed will be secured, that is to say, he will speak with profit and with power to effect his aim, while he will also win the praise not merely of the learned, but of the multitude as well.