Plato, Laws 881a

τῶν ὑπὸ γῆς τιμωριῶν λεγομένων, ἀλλὰ ὡς εἰδὼς ἃ μηδαμῶς οἶδεν, καταφρονῶν τῶν παλαιῶν καὶ ὑπὸ πάντων εἰρημένων, παρανομεῖ, τούτῳ δεῖ τινος ἀποτροπῆς ἐσχάτης. θάνατος μὲν οὖν οὐκ ἔστιν ἔσχατον, οἱ δὲ ἐν Ἅιδου τούτοισι λεγόμενοι πόνοι ἔτι τε τούτων εἰσὶ μᾶλλον ἐν ἐσχάτοις, καὶ ἀληθέστατα λέγοντες οὐδὲν ἀνύτουσιν ταῖς τοιαύταις ψυχαῖς ἀποτροπῆς—οὐ γὰρ ἂν ἐγίγνοντό ποτε μητραλοῖαί τε καὶ τῶν ἄλλων γεννητόρων ἀνόσιοι πληγῶν τόλμαι—δεῖ δὴ τὰς ἐνθάδε

(thinking he knows what he knows not at all), and shall thus transgress the law,—for such a man there is needed some most severe deterrent. Death is not a most severe penalty; and the punishments we are told of in Hades for such offences, although more severe than death and described most truly, yet fail to prove any deterrent to souls such as these,—else we should never find cases of matricide and of impiously audacious assaults