“A mind without instruction can no more bear fruit than can a field, however fertile, without cultivation.”
A: Quod est enim maius argumentum nihil eam prodesse quam quosdam perfectos philosophos turpiter vivere?
M: Nullum vero id quidem argumentum est. Nam ut agri non omnes frugiferi sunt qui coluntur [...] sic animi non omnes culti fructum ferunt. Atque, ut in eodem simili verser, ut ager quamvis fertilis sine cultura fructuosus esse non potest, sic sine doctrina animus; ita est utraque res sine altera debilis. Cultura autem animi philosophia est; haec extrahit vitia radicitus et praeparat animos ad satus accipiendos eaque mandat eis et, ut ita dicam, serit, quae adulta fructus uberrimos ferant.
Book II, Chapter V; translation by Andrew P. Peabody
Tusculanae Disputationes – Tusculan Disputations (45 BC)
Kontext: A: For what stronger proof can there be of its [philosophy's] uselessness than that some accomplished philosophers lead disgraceful lives?
M: It is no proof at all; for as all cultivated fields are not harvest-yielding [... ] so all cultivated minds do not bear fruit. To continue the figure – as a field, though fertile, cannot yield a harvest without cultivation, no more can the mind without learning; thus each is feeble without the other. But philosophy is the cultivation of the soul. It draws out vices by the root, prepares the mind to receive seed, and commits to it, and, so to speak, sows in it what, when grown, may bear the most abundant fruit.