Νόμος ἐστὶ Κείων, οἱ πάνυ παρ’ αὐτοῖς γεγηρακότες, ὥσπερ ἐπὶ ξένια παρακαλοῦντες ἑαυτοὺς ἢ επί τινα ἑορταστικὴν θυσίαν, συνελθόντες καὶ στεφανωσάμενοι πίνουσι κώνειον, ὅταν ἑαυτοῖς συνειδῶσιν ὅτι πρὸς τὰ ἔργα τὰ τῇ πατρίδι λυσιτελοῦντα ἄχρηστοί εἰσιν, ὑποληρούσης ἤδη τι αὐτοῖς καὶ τῆς γνώμης διὰ τὸν χρόνον.
(Aelian, Var. Hist. 3.37)
There is a law at Ceos that those who are extremely elderly invite each as if going to a party or to a festival with sacrifices, meet, put on garlands and drink hemlock. This they do when they become aware that they are incapable of performing tasks useful to their country, and that their judgment is by now rather feeble owing to the passing of time. (tr. Nigel G. Wilson)