The tongue as the devil's chief weapon
John Chrysostom is addressing the catechumens about their way of life before baptism, comparing their preparation to athletic training.
But when the time of the contests arrives, when the stadium is opened, when the theater above is seated, when the judge of the contest is present, then there is no choice: either you have been careless and you fall and retreat in great shame, or you have trained hard and you win the crowns and the prizes. So it is with you. These thirty days are like a wrestling school, like training grounds, like practice. Let us learn from this moment how to overcome that evil demon. For it is against him that we are going to strip for the contest after baptism; it is against him that we will box and fight. Let us learn from this moment, then, what his grips are, where his evil lies, where he can easily harm us, so that when the contests arrive we are not caught off guard or thrown into confusion at the sight of unfamiliar wrestling moves. Instead, having already practiced among ourselves and learned all his tactics, let us engage him in the wrestling with confidence.
He is accustomed to harm us from every direction, but especially through the tongue and through the mouth. For no instrument is so well suited to him for deceiving us and destroying us as an undisciplined tongue and a mouth without doors. From here come most of our falls; from here come our serious accusations. Someone, showing how easily slips happen through the tongue, said: "Many have fallen by the sword, but not so many as by the tongue" (Sirach 28:18). And the same person, showing how serious the fall is, said: "A slip on the floor is better than a slip of the tongue" (Sirach 20:18). What he means is this: It is better, he says, to fall and break your body than to let out a word that destroys our soul. And he does not only speak of the falls, but he also urges us to take great care so that we are not tripped up, saying: "Make a door and bars for your mouth" (Sirach 28:25)—not so that we build actual doors and bars, but so that with great security we shut the tongue against improper words. And again elsewhere, showing that along with our own effort we need help from above even before our own, the prophet lifted his hands to God and said: "The lifting up of my hands is an evening sacrifice. Set a guard, Lord, over my mouth, and a door of enclosure over my lips" (Psalm 141:2-3). And the one who gave the earlier advice also says: "Who will set a guard over my mouth, and a cunning seal over my lips?" (Sirach 22:27). Do you see how each one fears these falls, and laments them, and counsels, and prays that the tongue may enjoy great protection?
And why, someone says, if this instrument brings us so much destruction, did God put it in us in the beginning? Because it also has great usefulness. And if we are diligent, it has only usefulness and no destruction at all. Listen, then, to what the one who said those earlier things says: "In the hand of the tongue are life and death" (Proverbs 18:21). And Christ shows the same thing when he says: "By your words you will be condemned, and by your words you will be justified" (Matthew 12:37). For the tongue stands in the middle, able to be used for either purpose. You are its master. So too a sword lies in the middle: if you use it against enemies, the instrument has become your salvation; but if you thrust the blow against yourself, it is not the nature of the iron but your own lawlessness that causes the slaughter.
Greek
Ὅταν δὲ ὁ τῶν ἀγώνων παραγένηται καιρὸς, ὅταν ἀνοιγῇ τὸ στάδιον, ὅταν τὸ θέατρον ἄνω καθήμενον ᾖ, ὅταν ὁ ἀγωνοθέτης παρῇ, ἀνάγκη λοιπὸν ἢ ῥᾳθυμήσαντας πεσεῖν καὶ μετὰ αἰσχύνης ἀναχωρῆσαι πολλῆς, ἢ σπουδάσαντας τῶν στεφάνων καὶ τῶν βραβείων ἐπιτυχεῖν. Οὕτω δὴ καὶ ἐφ' ὑμῶν, αἱ τριάκοντα ἡμέραι αὗται παλαίστρᾳ τινὶ προσεοίκασι καὶ γυμνασίοις καὶ μελέτῃ. Μάθωμεν ἐντεῦθεν ἤδη περιγενέσθαι τοῦ πονηροῦ δαίμονος ἐκείνου· πρὸς γὰρ ἐκεῖνον ἀποδύεσθαι μέλλομεν μετὰ τὸ βάπτισμα, πρὸς ἐκεῖνον πυκτεύειν καὶ μάχεσθαι. Μάθωμεν τοίνυν ἐντεῦθεν ἤδη τὰς λαβὰς ἐκείνου, πόθεν ἐστὶ πονηρὸς, πόθεν ἡμῖν εὐκόλως ἐπηρεάσαι δύναται, ἵνα τῶν ἀγώνων παραγενομένων μὴ ξενοπαθῶμεν μηδὲ θορυβώμεθα, καινὰ τὰ παλαίσματα ὁρῶντες, ἀλλ' ἤδη μεταξὺ ἡμῶν αὐτῶν μελετήσαντες, καὶ τὰς μεθοδείας αὐτοῦ μαθόντες ἁπάσας, μετὰ τοῦ θαῤῥεῖν ἁψώμεθα τῶν παλαισμάτων πρὸς ἐκεῖνον. Πάντοθεν μὲν οὖν ἐπηρεάζειν ἡμῖν εἴωθεν, μάλιστα δὲ διὰ τῆς γλώττης καὶ διὰ τοῦ στόματος. Οὐδὲν γὰρ οὕτως ἐπιτήδειον ὄργανον ἐκείνῳ πρὸς ἀπάτην καὶ ἀπώλειαν ἡμετέραν, ὡς γλῶττα ἀκόλαστος καὶ στόμα ἀθύρωτον. Ἐντεῦθεν ἡμῖν τὰ πολλὰ πτώματα, ἐντεῦθεν ἡμῖν τὰ χαλεπὰ ἐγκλήματα. Καὶ τὴν μὲν εὐκολίαν τῶν ὀλισθημάτων διὰ τῆς γλώττης τις δηλῶν ἔλεγε· Πολλοὶ ἔπεσον διὰ μαχαίρας, ἀλλ' οὐ τοσοῦτοι ὅσοι διὰ γλώττης. Τὸ δὲ χαλεπὸν τοῦ πτώματος ἐμφαίνων πάλιν ὁ αὐτὸς εἶπεν· Ὀλίσθημα ἀπὸ ἐδάφους μᾶλλον, ἢ ὀλίσθημα ἀπὸ γλώσσης. Ὃ δὲ λέγει τοιοῦτόν ἐστι· Βέλτιόν ἐστι, φησὶ, πεσεῖν καὶ συντριβῆναι τὸ σῶμα, ἢ ῥῆμα προέσθαι τοιοῦτον, ὃ τὴν ψυχὴν ἡμῶν ἀπόλλυσιν. Οὐ λέγει δὲ τὰ πτώματα μόνον, ἀλλὰ καὶ παραινεῖ πολλὴν ποιεῖσθαι πρόνοιαν, ὥστε μὴ ὑποσκελισθῆναι, οὕτως εἰπών· Ποίησον τῷ στόματί σου θύραν καὶ μοχλούς· οὐχ ἵνα θύρας καὶ μοχλοὺς κατασκευάσωμεν, ἀλλ' ἵνα μετὰ πολλῆς τῆς ἀσφαλείας πρὸς τὰ ἄτοπα τῶν ῥημάτων τὴν γλῶτταν ἀποκλείσωμεν. Καὶ πάλιν ἀλλαχοῦ δεικνὺς, ὅτι μετὰ τῆς ἡμετέρας σπουδῆς, καὶ πρὸ τῆς ἡμετέρας τῆς ἄνωθεν δεόμεθα ῥοπῆς, ὥστε τὸ θηρίον τοῦτο κατασχεῖν ἔνδον, πρὸς τὸν Θεὸν τὰς χεῖρας ἀνατείνας ὁ προφήτης ἔλεγεν· Ἔπαρσις τῶν χειρῶν μου θυσία ἑσπερινή. Θοῦ, Κύριε, φυλακὴν τῷ στόματί μου, καὶ θύραν περιοχῆς ἐπὶ τὰ χείλη μου. Ὁ δὲ τὰ πρότερον παραινέσας, πάλιν καὶ αὐτός φησι· Τίς δώσει ἐπὶ τῷ στόματί μου φυλακὴν, καὶ ἐπὶ τῶν χειλέων μου σφραγῖδα πανοῦργον; Ὁρᾷς ἕκαστον δεδοικότα τὰ πτώματα ταῦτα, καὶ θρηνοῦντα καὶ συμβουλεύοντα, καὶ εὐχόμενον πολλῆς ἀπολαῦσαι τὴν γλῶτταν φυλακῆς; Καὶ τίνος ἕνεκεν, φησὶν, εἰ τοσοῦτον ἡμῖν φέρει τὸν ὄλεθρον τοῦτο τὸ ὄργανον, ἐνέθηκεν ἡμῖν αὐτὸ παρὰ τὴν ἀρχὴν ὁ Θεός; Ὅτι καὶ πολλὴν ἔχει τὴν ὠφέλειαν· κἂν σπουδάζωμεν, ὠφέλειαν ἔχει μόνον, ὄλεθρον δὲ οὐδένα. Ἄκουσον γοῦν τί φησιν ὁ τὰ πρότερα ἐκεῖνα εἰπών· Ἐν χειρὶ γλώττης ζωὴ καὶ θάνατος. Καὶ ὁ Χριστὸς δὲ τὰ αὐτὰ δηλοῖ λέγων· Ἀπὸ τῶν λόγων σου κατακριθήσῃ, καὶ ἀπὸ τῶν λόγων σου δικαιωθήσῃ. Μέσῃ γὰρ ἕστηκεν ἡ γλῶσσα τῆς πρὸς ἑκάτερα χρήσεως· σὺ κύριος εἶ. Οὕτω καὶ τὸ ξίφος κεῖται μέσον· κἂν μὲν κατὰ τῶν πολεμίων χρήσῃ σωτήριόν σοι τὸ ὄργανον γέγονεν· ἂν δὲ κατὰ σαυτοῦ τὴν πληγὴν ὠθήσῃς, οὐχ ἡ σιδήρου φύσις, ἀλλ' ἡ σὴ παρανομία γίνεται τῆς σφαγῆς αἰτία.