Now the only sure basis of an alliance is for each party to be equally afraid of the other... - Thucydides

You may be sure that we are as well aware as you of the difficulty of contending against your power and fortune, unless the terms be equal. But we trust that the gods may grant us fortune as good as yours, since we are just men fighting against unjust, and that what we want in power will be made up by the alliance of the Lacedaemonians, who are bound, if only for very shame, to come to the aid of their kindred. Our confidence, therefore, after all is not so utterly irrational.

(Peloponnesian Generals:) The skill (ἐπιστήμη) of your enemies which you so greatly dread, if united with courage (ἀνδρείαν), may be able in the moment of danger to remember and execute the lesson which it has learned, but without courage (εὐψυχίας) no skill (τέχνη) can do anything at such a time.

τῶνδε δὲ ἡ ἐπιστήμη, ἣν μάλιστα φοβεῖσθε, ἀνδρείαν μὲν ἔχουσα καὶ μνήμην ἕξει ἐν τῷ δεινῷ ἐπιτελεῖν ἃ ἔμαθεν, ἄνευ δὲ εὐψυχίας οὐδεμία τέχνη πρὸς τοὺς κινδύνους ἰσχύει.

For fear makes men forget, and skill which cannot fight (ἀλκῆς) is useless.

φόβος γὰρ μνήμην ἐκπλήσσει, τέχνη δὲ ἄνευ ἀλκῆς οὐδὲν ὠφελεῖ.

(Book 2 Chapter 87.4)

(Corinthians:) The spirit of trust, Lacedaemonians, which animates your own political and social life, makes you distrust others who, like ourselves, have something unpleasant to say, and this temper of mind, though favourable to moderation, too often leaves you in ignorance of what is going on outside your own country, but instead of taking our words to heart, you chose to suspect that we only spoke from interested motives.