Plato, Laws 849b

εἰ γίγνεται κατὰ τὸν νόμον ἕκαστα. νόμος δʼ ἑκάστῳ μηνὸς τῇ νέᾳ ὧν δεῖ πραθῆναι τὸ μέρος τοῖς ξένοις ἐξάγειν τοὺς ἐπιτρόπους, ὅσοι τοῖς ἀστοῖς ξένοι ἢ καὶ δοῦλοι ἐπιτροπεύουσι, δωδεκατημόριον πρῶτον τοῦ σίτου, τὸν δὲ ξένον εἰς πάντα τὸν μῆνα ὠνεῖσθαι σῖτον μὲν καὶ ὅσα περὶ σῖτον ἀγορᾷ τῇ πρώτῃ· δεκάτῃ δὲ τοῦ μηνὸς τὴν τῶν ὑγρῶν οἱ μὲν πρᾶσιν, οἱ δὲ ὠνὴν ποιείσθωσαν διʼ ὅλου τοῦ μηνὸς ἱκανήν·

are directed to make to foreigners are always legally conducted. There shall be this one law—that on the first day of the month the portion of the goods which is to be sold to foreigners shall be brought out by the managers—that is, the foreigners or slaves who act as managers for the citizens; and the first commodity shall be the twelfth share of corn, and the foreigner shall buy corn, and all that goes with it, at this first market. On the tenth day of the month, fluids sufficient to last through the month shall be sold by the one party and bought by the other. Thirdly, on the twentieth day, there shall be a sale of live-stock, as much as each party