Plato, Laws 809d

ταῦτα πάσῃ πόλει—τίνων δὴ πέρι λέγομεν; ἡμερῶν τάξεως εἰς μηνῶν περιόδους καὶ μηνῶν εἰς ἕκαστον τὸν ἐνιαυτόν, ἵνα ὧραι καὶ θυσίαι καὶ ἑορταὶ τὰ προσήκοντʼ ἀπολαμβάνουσαι ἑαυταῖς ἕκασται τῷ κατὰ φύσιν ἄγεσθαι, ζῶσαν τὴν πόλιν καὶ ἐγρηγορυῖαν παρεχόμεναι, θεοῖς μὲν τὰς τιμὰς ἀποδιδῶσιν, τοὺς δὲ ἀνθρώπους περὶ αὐτὰ μᾶλλον ἔμφρονας ἀπεργάζωνται—ταῦτα οὔπω σοι πάντα ἱκανῶς, ὦ φίλε, παρὰ

is obliged to take them into account. What I allude to is this—the arranging of days into monthly periods, and of months into a year, in each instance, so that the seasons, with their respective sacrifices and feasts, may each be assigned its due position by being held as nature dictates, and that thus they may create fresh liveliness and alertness in the State, and may pay their due honors to the gods, and may render the citizens more intelligent about these matters. These points, my friend, have not all as yet been explained to you sufficiently by the lawgiver.