Polybius, Histories 1.14:
“I was not goaded on to writing an account of this war by the aforesaid reasons any less than I was by the fact that those who seem to have written most learnedly about it – Philinus and Fabius – have not given us the truth as they ought to. I would not undertake to say that they lied willingly, given what I know about their life and conduct. But they seem to me to have suffered what is common to lovers. Because of Philinus’ partisanship and good feeling for the Carthaginians, he feels that they did everything wisely, nobly, and manfully, while the Romans lacked all of those qualities. Of course, the opposite holds true for Fabius. In the rest of life, one would not so readily abandon that sense of fairness. Indeed, it befits a philosophical person to be a friend to his friends, a good person and a patriot who shares a hatred of enemies with those friends while he loves those friends in equal measure. But when someone takes on the subject of history, they should forget about all of that shit. It will be necessary on many occasions to speak well of the enemy and fluff them up with the greatest encomia when the occasion demands it, and similarly it will be necessary to reprove and chastise one’s closest relations in unsparing fashion when their failures warrant it.”
οὐχ ἧττον δὲ τῶν προειρημένων παρωξύνθην ἐπιστῆσαι τούτῳ τῷ πολέμῳ καὶ διὰ τὸ τοὺς ἐμπειρότατα δοκοῦντας γράφειν ὑπὲρ αὐτοῦ, Φιλῖνον καὶ Φάβιον, μὴ δεόντως ἡμῖν ἀπηγγελκέναι τὴν ἀλήθειαν. ἑκόντας μὲν οὖν ἐψεῦσθαι τοὺς ἄνδρας οὐχ ὑπολαμβάνω, στοχαζόμενος ἐκ τοῦ βίου καὶ τῆς αἱρέσεως αὐτῶν: δοκοῦσι δέ μοι πεπονθέναι τι παραπλήσιον τοῖς ἐρῶσι. [διὰ γὰρ τὴν αἵρεσιν καὶ τὴν ὅλην εὔνοιαν Φιλίνῳ μὲν πάντα δοκοῦσιν οἱ Καρχηδόνιοι πεπρᾶχθαι φρονίμως, καλῶς, ἀνδρωδῶς, οἱ δὲ Ῥωμαῖοι τἀναντία, Φαβίῳ δὲ τοὔμπαλιν τούτων. ἐν μὲν οὖν τῷ λοιπῷ βίῳ τὴν τοιαύτην ἐπιείκειαν ἴσως οὐκ ἄν τις ἐκβάλλοι: καὶ γὰρ φιλόφιλον εἶναι δεῖ τὸν ἀγαθὸν ἄνδρα καὶ φιλόπατριν καὶ συμμισεῖν τοῖς φίλοις τοὺς ἐχθροὺς καὶ συναγαπᾶν τοὺς φίλους: ὅταν δὲ τὸ τῆς ἱστορίας ἦθος ἀναλαμβάνῃ τις, ἐπιλαθέσθαι χρὴ πάντων τῶν τοιούτων καὶ πολλάκις μὲν εὐλογεῖν καὶ κοσμεῖν τοῖς μεγίστοις ἐπαίνοις τοὺς ἐχθρούς, ὅταν αἱ πράξεις ἀπαιτῶσι τοῦτο, πολλάκις δ᾽ ἐλέγχειν καὶ ψέγειν ἐπονειδίστως τοὺς ἀναγκαιοτάτους, ὅταν αἱ τῶν ἐπιτηδευμάτων ἁμαρτίαι τοῦθ᾽ ὑποδεικνύωσιν.