30. But when, as the two advanced to man's estate, they began to handle the doctrines of philosophy (which I wish they had never done), and were deriving that power from words which to the good is the weapon of virtue, but to the ill-conditioned the incentive to vice, this man was no longer able to restrain his disease in every part, nor to plan within himself alone the plot of his impiety in all its completeness; but like as fire smouldering in wood, even though it does not rise into a bright flame, either sparks flying out, or smoke from the inside, give warning of the mischief; or, if you like it better, as certain water-springs that run through subterranean channels by the aid of air, and then, not having sufficient room nor a free passage, burst forth in many places of the ground, and gurgle out from below, being forced upwards by the strength of the air, but checked and repelled by the weight above; in the same way did he conceal the most part of his impiety, by reason of the times and the superintendence of one stronger than himself (for as yet it was not safe to be impious); still, in some points he exposed the secret of his thoughts; and, to the more sharpsighted, his impiety rather than his intelligence, by exerting himself in advocacy of the Pagans, in his disputations against his brother, to a greater degree than was becoming----on the pretext, forsooth, that he was practising upon the weaker argument; but this was in reality an exercising of himself against the Truth, and a delighting in everything by which an impious disposition is characterized.  

Λʹ. Ἐπεὶ δὲ εἰς ἄνδρας προϊόντες ἤδη τῶν ἐν φιλοσοφίᾳ δογμάτων ἥψαντο (ὡς μήποτε ὤφελον!) καὶ τὴν ἐκ τοῦ λόγου προσελάμβανον δύναμιν, ἢ τοῖς μὲν ἐπιεικέσιν ἀρετῆς ὅπλον, τοῖς δὲ μοχθηροτέροις κέντρον κακίας γίνεται, οὐκέτι κατέχειν ὅλην τὴν νόσον οἷός τε ἦν, οὐδὲ παντελῶς τὸν τῆς ἀσεβείας δόλον ἐν ἑαυτῷ μόνῳ φιλοσοφεῖν: ἀλλ' ὥσπερ πῦρ ἐμφωλεῦον ὕλῃ, κἂν μήπω πρὸς φλόγα λαμπρὰν ἀρθῇ, σπινθῆρές τινες ἐξάπτοντες ἢ καπνὸς ἐκ βάθους ὑποσημαίνουσιν: εἰ βούλει δὲ, τῶν πηγῶν αἳ σήραγγάς τινας ὑποτρέχουσαι μετὰ πνεύματος, εἶτ' εὐρυχωρίαν οὐκ ἔχουσαι, οὐδὲ διέξοδον ἐλευθέραν, πολλαχοῦ τῆς γῆς ἀναφυσῶσι καὶ ὑπηχοῦσι κάτωθεν, ὑπὸ μὲν τῆς τοῦ πνεύματος ἀνωθούμεναι, ὑπὸ δὲ τῆς ἄνωθεν βίας κατεχόμεναί τε καὶ ἀνακοπτόμεναι: οὕτω καὶ αὐτὸς τὸ μὲν πολὺ τῆς ἀσεβείας κατέκρυπτεν ὑπὸ τοῦ καιροῦ καὶ τῆς τοῦ κρατοῦντος παιδαγωγίας: οὔπω γὰρ τὸ φανερῶς ἀσεβεῖν ἦν ἀσφαλές: ἔστι δὲ ὅποι καὶ παρεγύμνου τὸ τῆς γνώμης ἀπόῤῥητον τοῖς ὀξυτέροις τὴν ἀσέβειαν ἢ τὴν σύνεσιν: ἔν τε τοῖς πρὸς τὸν ἀδελφὸν λόγοις πλέον ἢ καλῶς εἶχεν, ὑπὲρ Ἑλλήνων διατεινόμενος (προφάσει δῆθεν ὡς τὸν ἥττω γυμνάζων λόγον, τὸ δὲ ἦν ὄντως γυμνασία κατὰ τῆς ἀληθείας), καὶ πᾶσι χαίρων οἷς ἀσεβὴς τρόπος χαρακτηρίζεται.