Or, Thucydides says it all
from Thucydides 3.82.2-5
“Many terrible things happened to the cities during the revolution, as it always has been and always will be, as long as human nature is the same, although it sometimes takes a harsher or more mild form as the changes arise in different cities. During peace and times of abundance, cities and individual citizens have better ideas since they do not experience the compulsion of scarcity. But war, in depriving them of their daily needs, is a forceful teacher, and makes the character of most people equal to their present conditions.
Thus, the cities were in states of revolution and the places where it developed later pursued greater excess in their innovations from hearing of its coming beforehand—in both the cleverness of their attempts and the inappropriateness of their retributions.
The regular meaning of words changed to fit the state of affairs. Insane risk was now bravery for an ally; careful forethought was cowardice; moderation was considered an excuse for being unmanly; circumspection was an unwillingness to commit; heedless attacks was termed manly behavior, and self-defense was a bland excuse for conspiracy.
The one seeking extreme action was considered trustworthy; anyone who spoke against him was suspicious. If you were a successful conspirator, you were smart; you were clever if you discovered a conspiracy. But if you made provisions against either situation, you risked dividing your party and living in fear of your opponents. It was simply the same whether you stopped someone from doing wrong or you discovered a new opportunity for wrongdoing.”
 καὶ ἐπέπεσε πολλὰ καὶ χαλεπὰ κατὰ στάσιν ταῖς πόλεσι, γιγνόμενα μὲν καὶ αἰεὶ ἐσόμενα, ἕως ἂν ἡ αὐτὴ φύσις ἀνθρώπων ᾖ, μᾶλλον δὲ καὶ ἡσυχαίτερα καὶ τοῖς εἴδεσι διηλλαγμένα, ὡς ἂν ἕκασται αἱ μεταβολαὶ τῶν ξυντυχιῶν ἐφιστῶνται. ἐν μὲν γὰρ εἰρήνῃ καὶ ἀγαθοῖς πράγμασιν αἵ τε πόλεις καὶ οἱ ἰδιῶται ἀμείνους τὰς γνώμας ἔχουσι διὰ τὸ μὴ ἐς ἀκουσίους ἀνάγκας πίπτειν: ὁ δὲ πόλεμος ὑφελὼν τὴν εὐπορίαν τοῦ καθ᾽ ἡμέραν βίαιος διδάσκαλος καὶ πρὸς τὰ παρόντα τὰς ὀργὰς τῶν πολλῶν ὁμοιοῖ.
 ἐστασίαζέ τε οὖν τὰ τῶν πόλεων, καὶ τὰ ἐφυστερίζοντά που πύστει τῶν προγενομένων πολὺ ἐπέφερε τὴν ὑπερβολὴν τοῦκαινοῦσθαι τὰς διανοίας τῶν τ᾽ ἐπιχειρήσεων περιτεχνήσει καὶ τῶν τιμωριῶν ἀτοπίᾳ.
 καὶ τὴν εἰωθυῖαν ἀξίωσιν τῶν ὀνομάτων ἐς τὰ ἔργα ἀντήλλαξαν τῇ δικαιώσει. τόλμα μὲν γὰρ ἀλόγιστος ἀνδρεία φιλέταιρος ἐνομίσθη, μέλλησις δὲ προμηθὴς δειλία εὐπρεπής, τὸ δὲ σῶφρον τοῦ ἀνάνδρου πρόσχημα, καὶ τὸ πρὸς ἅπαν ξυνετὸν ἐπὶ πᾶν ἀργόν· τὸ δ’ ἐμπλήκτως ὀξὺ ἀνδρὸς μοίρᾳ προσετέθη, ἀσφαλείᾳ δὲ τὸ ἐπιβουλεύσασθαι ἀποτροπῆς πρόφασις εὔλογος.
 καὶ ὁ μὲν χαλεπαίνων πιστὸς αἰεί, ὁ δ᾽ ἀντιλέγων αὐτῷ ὕποπτος. ἐπιβουλεύσας δέ τις τυχὼν ξυνετὸς καὶ ὑπονοήσας ἔτιδεινότερος: προβουλεύσας δὲ ὅπως μηδὲν αὐτῶν δεήσει, τῆς τε ἑταιρίας διαλυτὴς καὶ τοὺς ἐναντίους ἐκπεπληγμένος. ἁπλῶς δὲὁ φθάσας τὸν μέλλοντα κακόν τι δρᾶν ἐπῃνεῖτο, καὶ ὁ ἐπικελεύσας τὸν μὴ διανοούμενον.