History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
"To an individual, however, who has absolute power, or to a state that holds dominion, nothing is inconsistent that is profitable, nothing reckoned as kindred that does not command confidence; but in every case, as opportunity may serve, you must become either a foe or a friend. And in our case, our advantage here consists in this,—not that we should reduce our friends to weakness, but that, owing to the strength of our friends, our foes should be powerless. Nor ought you to doubt this.
For even in the case of our allies in those parts, as they are severally useful to us, so we govern them; the Chians and Methymnaeans as independent, on condition of their supplying ships; the greater part of them on more stringent terms, subject to contribution of money; but others, although they are islanders and easy to reduce, as allies on terms of entire freedom, because they he in favourable positions around the Peloponnese.
So that here also it is natural that we should regulate them with an eye to our advantage, and, as we say, with reference to our fear of the Syracusans. For they are aiming at dominion over you, and wish, after uniting you on the strength of your suspicions of us, themselves to sway the empire of Sicily, by force, or through your forlorn condition, when we have departed without gaining our object. And it must be so, if you unite with them; for neither will so great a force, when united, be any longer easy for us to manage, nor would these men want strength to deal with you, when we were not here.
"And whoever does not think this to be the case, the very fact itself convicts him of being wrong. For on a former occasion you called us to your aid by holding out to us no other fear, than that, if we permitted you to fall under the Syracusans, we ourselves also should be exposed to danger.
It is not right therefore now, that you should refuse to be persuaded by that self-same argument by which you wished to persuade us; or that, because we are come with a larger armament, you should be suspicious of us; but much rather, that you should mistrust these men.