Thucydides, History of the Peloponnesian War
Benjamin Jowett, Ed.

82. 'We had come to renew our former alliance, but the attack made upon us by the Syracusan envoy renders it necessary for us to vindicate our title to empire¹. [2] He himself bore the strongest witness in² our favour when he said that Dorians and Ionians are inveterate enemies. And so they are. We Ionians dwelling in the neighbourhood of the Peloponnesians (who are Dorians and more numerous than ourselves) have had to consider the best way of securing ourindependence. [3] After the Persian War we were delivered by the help of our newly-acquired navy from the rule and supremacy of Lacedaemon; they had no more right to domineer over us than we over them, except the right of the stronger, which at the time they possessed. We then assumed the leadership of the King's former subjects, which we still retain; if we were not to be the slaves of the Peloponnesians we thought that we must have the means of self-defence. And what if we did subjugate those kinsmen of ours whom the Syracusans say that we have enslaved, the Ionians and the islanders? On the strictest principles, where was the injustice? [4] For we were their mother-city, and they joined in the Persian invasion. They had not the courage to revolt from him and to destroy their homes, as we did when we left our city. But they chose slavery for their own portion, and would have imposed it upon us.