Lucian, Dialogues of the Dead
6.2 (Terpsion speaking; tr. M.D. MacLeod):
Then I object to the present arrangement. It ought to be a matter of turn, with the oldest man first, and after him the next oldest, without the slightest change in the order. Your Methuselah shouldn't live on, when he has no more than three teeth still left, and is scarcely able to see, supported by four servants, with his nose always running and his eyes bleary, past knowing any of the pleasures of life, a living tomb laughed at by the young men. He shouldn't live, while handsome lusty young men die. That's as unnatural as "rivers running backwards".
Οὐκοῦν ταύτης αἰτιῶμαι τῆς διατάξεως· ἐχρῆν γὰρ τὸ πρᾶγμα ἑξῆς πως γίνεσθαι, τὸν πρεσβύτερον πρότερον καὶ μετὰ τοῦτον ὅστις καὶ τῇ ἡλικίᾳ μετ΄ αὐτόν, ἀναστρέφεσθαι δὲ μηδαμῶς, μηδὲ ζῆν μὲν τὸν ὑπέργηρων ὀδόντας τρεῖς ἔτι λοιποὺς ἔχοντα, μόγις ὁρῶντα, οἰκέταις γε τέτταρσιν ἐπικεκυφότα, κορύζης μὲν τὴν ῥῖνα, λήμης δὲ τοὺς ὀφθαλμοὺς μεστὸν ὄντα, οὐδὲν ἔτι ἡδὺ εἰδότα, ἔμψυχόν τινα τάφον ὑπὸ τῶν νέων καταγελώμενον, ἀποθνήσκειν δὲ καλλίστους καὶ ἐρρωμενεστάτους νεανίσκους· ἄνω γὰρ ποταμῶν τοῦτό γε.