"Of Old Age". Book by Marcus Tullius Cicero, book 5, section 15, reported in "Cicero on the Art of Growing Old", book by Herbert N. Couch (1959), p. 21,
Marcus Tullius Cicero (1855). “Cicero's Three books of offices, or moral duties: also his Cato Major, an essay on old age; Lælius, an essay on friendship; Paradoxes; Scipio's dream; and Letter to Quintus on the duties of a magistrate”, p.250