History of the Peloponnesian War

Nor are you they that first break the peace, which the God, inasmuch as he doth encourage us to the war, judgeth violated by them; but you fight rather in defence of the same. For not he breaketh the peace that taketh revenge, but he that is the first invader.

So that seeing it will be every way good to make the war, and since in common we persuade the same, and seeing also that both to the cities and to private men it will be the most profitable course, put off no longer neither the defence of the Potidaeans, who are Dorians and besieged (which was wont to be contrary) by lonians, nor the recovery of the liberty of the rest of the Grecians. For it is a case that admitteth not delay when they are some of them already oppressed, and others (after it shall be known we met and durst not right ourselves) shall shortly after undergo the like.