Bellum Omnium Contra Omnes

Plato, Laws 1.625e-626a (tr. Trevor Saunders; Clinias speaking, he = Minos):

In this, I think, he censured the stupidity of ordinary men, who do not understand that they are all engaged in a never-ending lifelong war against all other states. So, if you grant the necessity of eating together for self-protection in war-time, and of appointing officers and men in turn to act as guards, the same thing should be done in peace-time too. The legislator's position would be that what most men call 'peace' is really only a fiction, and that in cold fact all states are by nature fighting an undeclared war against every other state.

ἄνοιαν δή μοι δοκεῖ καταγνῶναι τῶν πολλῶν ὡς οὐ μανθανόντων ὅτι πόλεμος ἀεὶ πᾶσιν διὰ βίου συνεχής ἐστι πρὸς ἁπάσας τὰς πόλεις· εἰ δὴ πολέμου γε ὄντος φυλακῆς ἕνεκα δεῖ συσσιτεῖν καί τινας ἄρχοντας καὶ ἀρχομένους διακεκοσμημένους εἶναι φύλακας αὐτῶν, τοῦτο καὶ ἐν εἰρήνῃ δραστέον. ἣν γὰρ καλοῦσιν οἱ πλεῖστοι τῶν ἀνθρώπων εἰρήνην, τοῦτ᾽ εἶναι μόνον ὄνομα, τῷ δ᾽ ἔργῳ πάσαις πρὸς πάσας τὰς πόλεις ἀεὶ πόλεμον ἀκήρυκτον κατὰ φύσιν εἶναι.