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 indeed even although geometricians, musicians and grammarians, together with the professors of every other branch of knowledge, spend all their lives, however long, in the study of one single science, it does not therefore follow that we require several lives more if we are to learn more. For they do not spend all their days even to old age in learning these things, but being content to have learned these things and nothing more, exhaust their length of years not in acquiring, but in imparting knowledge.
However, to say nothing of Homer, in whom we may find either the perfect achievements, or at any rate clear signs of the knowledge of every art,
Again in what branch of knowledge worthy of literary expression was Plato deficient? How many generations' study did Aristotle require to embrace not merely the whole range of philosophical and rhetorical knowledge, but to investigate the nature of every beast and plant. And yet they had to discover all these things which we only have to learn. Antiquity has given us all these teachers and all these patterns for our imitation, that there might be no greater happiness conceivable than to be born in this age above all others, since all previous ages have toiled that we might reap the fruit of their wisdom.