Plato, Laws 758d

ἂν μάλιστα μὲν μὴ γίγνωνται, γενομένων δέ, ὅτι τάχιστα αἰσθομένης τῆς πόλεως ἰαθῇ τὸ γενόμενον· διʼ ἃ συλλογῶν τε ἀεὶ δεῖ τοῦτο εἶναι τὸ προκαθήμενον τῆς πόλεως κύριον καὶ διαλύσεων, τῶν τε κατὰ νόμους τῶν τε ἐξαίφνης προσπιπτουσῶν τῇ πόλει. ταῦτα μὲν οὖν πάντα τὸ δωδέκατον ἂν μέρος τῆς βουλῆς εἴη τὸ διακοσμοῦν, τὰ ἕνδεκα ἀναπαυόμενον τοῦ ἐνιαυτοῦ μέρη· κοινῇ δὲ μετὰ τῶν ἄλλων ἀρχῶν δεῖ τὰς φυλακὰς ταύτας φυλάττειν κατὰ πόλιν τοῦτο τὸ μόριον τῆς βουλῆς ἀεί.καὶ τὰ μὲν κατὰ πόλιν οὕτως ἔχοντα μετρίως ἂν εἴη

and in case they do occur, to ensure that the State may perceive and remedy the occurrence as quickly as possible. For these reasons, this presidential section of the State must always have the control of the summoning and dissolving of assemblies, both the regular legal assemblies and those of an emergency character. Thus a twelfth part of the Council will be the body that manages all these matters, and each such part shall rest in turn for eleven-twelfths of the year: in common with the rest of the officials, this twelfth section of the Council must keep its watch in the State over these matters continually. This disposition of affairs in the city will prove a reasonable arrangement.