History of the Peloponnesian War

"Now to a tyrant or city that reigneth, nothing can be thought absurd if profitable, nor any man a friend that may not be trusted to. Friend or enemy he must be, according to the several occasions. But here it is for our benefit not to weaken our friends, but by our friends' strength to weaken our enemies. This you must needs believe, inasmuch as yonder also we so command over our confederates as every of them may be most useful to us:

the Chians and Methymnaeans redeem their liberty with providing us some galleys; the most of the rest, with a tribute of money somewhat more pressing. Some again of our confederates are absolutely free, notwithstanding that they be islanders and easy to be subdued; the reason whereof is this: they are situate in places commodious about Peloponnesus.

It is probable, therefore, that here also we will so order our affairs as shall be most for our own turn and most according to our fear, as we told you, of the Syracusians. For they affect a dominion over you, and having by advantage of your suspicion of us drawn you to their side, will themselves by force, or (if we go home without effect) by your want of friends, have the sole command of Sicily, which, if you join with them, must of necessity come to pass. For neither will it be easy for us to bring so great forces again together, nor will the Syracusians want strength to subdue you if we be absent. Him that thinketh otherwise, the thing itself convinceth.