History of the Peloponnesian War

Fear perhaps will make you study to do right both by us and by the invaders, and plead that you have an alliance with the Athenians. But you made that alliance, not against your friends, but against the enemies that might attack you, and to help the Athenians when they were wronged by others, not when as now they are wronging their neighbours.

Even the Rhegians, Chalcidians though they be, refuse to help to restore the Chalcidian Leontines; and it would be strange if, while they suspect the gist of this fine pretence and are wise without reason, you, with every reason on your side, should yet choose to assist your natural enemies, and should join with their direst foes in undoing those whom nature has made your own kinsfolk.

This is not to do right; but you should help us without fear of their armament, which has no terrors if we hold together, but only if we let them succeed in their endeavours to separate us; since even after attacking us by ourselves and being victorious in battle, they had to go off without effecting their purpose.