• The English translation is by The History of Greek Mathematics by Thomas Little Heath (1921), p. 357. The quote is recorded by Stobaeus' Florilegium iv, 114 (ed. Teubner 1856, p. 205; see also here). Stobaeus attributes the anecdote to Serenus.
Give him threepence, since he must make gain out of what he learns. (Δός αὐτῷ τριώβολον, ἐπειδὴ δεῖ αὐτῷ ἐξ ὧν μανθάνει κερδαίνειν)
• Said to be a remark made to his servant when a student asked what he would get out of studying geometry.
What It Means
This is a placeholder explanation generated by the low-overhead model. It interprets "Give him threepence, since he must make gain out of what he learns. (Δός αὐτῷ τριώβολον, ἐπειδὴ δεῖ αὐτῷ ἐξ ὧν μανθάνει κερδαίνειν)
• Said to be a remark made to his servant when a student asked what he would get out of studying geometry." in the context of "'threepence' renders τριώβολον "three-obol-piece". This amount increases the sarcasm of Euclid's reply, as it was the standard fee of a Dikastes for attending a court case (μίσθος δικαστικός), thus inverting the role of teacher and pupil to that of accused and juror.
• The English translation is by The History of Greek Mathematics by Thomas Little Heath (1921), p. 357. The quote is recorded by Stobaeus' Florilegium iv, 114 (ed. Teubner 1856, p. 205; see also here). Stobaeus attributes the anecdote to Serenus." to mean that wisdom is timeless.
About Euclid