Plato, Laws 870d

εἰσὶν ἐξειργασμένοι, ὅταν ᾖ τῳ πραττόμενα ἢ πεπραγμένα ἃ μηδένα βούλονταί σφισιν συνειδέναι γιγνόμενα ἢ γεγονότα· τοὺς οὖν τούτων μηνυτὰς ἀναιροῦσι θανάτοις, ὅταν ἄλλῳ μηδενὶ δύνωνται τρόπῳ. τούτων δὴ πάντων πέρι προοίμια μὲν εἰρημένα ταῦτʼ ἔστω, καὶ πρὸς τούτοις, ὃν καὶ πολλοὶ λόγον τῶν ἐν ταῖς τελεταῖς περὶ τὰ τοιαῦτα ἐσπουδακότων ἀκούοντες σφόδρα πείθονται, τὸ τῶν τοιούτων τίσιν ἐν Ἅιδου

have wrought many murders,—in cases where men do or have done things concerning which they desire that no one should share their secret; consequently, if there are any who might expose their secret, they remove them by death, whenever they can do so by no other means. Concerning all these matters, the preludes mentioned shall be pronounced, and, in addition to them, that story which is believed by many when they hear it from the lips of those who seriously relate such things at their mystic rites,—that vengeance for such acts is exacted in Hades, and that those who return again to this earth are bound to pay