Plato, Laws 924c

ὀρφανῶν πεντεκαίδεκα τῶν νομοφυλάκων οἱ πρεσβύτατοι πάντων ἐπιμελείσθων ἀεὶ κατὰ πρέσβιν καὶ κατὰ τρεῖς διελόμενοι σφᾶς αὐτούς, κατʼ ἐνιαυτὸν τρεῖς καὶ κατʼ ἐνιαυτὸν ἄλλον ἕτεροι τρεῖς, ἕως ἂν αἱ πέντε περίοδοι γίγνωνται κύκλῳ· καὶ τοῦτο ἐκλιπέτω μηδέποτε κατὰ δύναμιν.ὃς δʼ ἂν μηδὲν τὸ παράπαν διαθέμενος ἀποθάνῃ, παῖδας μὲν καταλιπὼν δεομένους ἐπιτροπῆς, τῶν αὐτῶν νόμων τούτων

All that appertains to guardianship and the orphans shall be supervised by fifteen of the Law-wardens, who shall be the eldest of the whole body, and shall divide themselves into threes according to seniority, three acting one year and another three a second year, until five yearly periods have passed in rotation; and this process shall go on, so far as possible, without a break. And if any man die wholly intestate, leaving children that require guardianship, his unfriended children shall share in these same laws.