Plato, Laws 760d

ἑκάστου μηνὸς ἡγεῖσθαι τοὺς φρουράρχους ἐπὶ δεξιὰ κύκλῳ· τὸ δʼ ἐπὶ δεξιὰ γιγνέσθω τὸ πρὸς ἕω. περιελθόντος δὲ τοῦ ἐνιαυτοῦ, τῷ δευτέρῳ ἔτει, ἵνα ὡς πλεῖστοι τῶν φρουρῶν μὴ μόνον ἔμπειροι τῆς χώρας γίγνωνται κατὰ μίαν ὥραν τοῦ ἐνιαυτοῦ, πρὸς τῇ χώρᾳ δὲ ἅμα καὶ τῆς ὥρας ἑκάστης περὶ ἕκαστον τὸν τόπον τὸ γιγνόμενον ὡς πλεῖστοι καταμάθωσιν, οἱ τότε ἡγούμενοι πάλιν ἀφηγείσθωσαν εἰς τὸν εὐώνυμον

and that will be from west to east. When the first year is completed, in order that as many as possible of the guards may not only become familiar with the country in one season of the year, but may also learn about what occurs in each several district at different seasons, their leaders shall lead them back again in the reverse direction, constantly