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

87. 'So careful are we where our highest interests are at stake. And not to speak of our oaths,¹ you cannot have better assurance that they give whose actions, when compared with their professions, afford a convincing proof that it is their interest to keep their word. [2] 'But if you plead that you cannot accept the proposals which I offer, and insist that you ought not to suffer for the rejection of them because you are our friends; if you are of opinion that liberty is perilous and should not in justice be forced upon any one, but gently brought to those who are able to receive it,—I shall first call the Gods and heroes of the country to witness that I have come hither for your good, and that you would not be persuaded by me: I shall then use force and ravage your country without any more scruple. [3] I shall deem myself justified by two overpowering arguments. In the first place, I must not permit the Lacedaemonians to suffer by your friendship, and suffer they will through the revenues which the Athenians will continue to derive from you if you do not join me; and in the second place, the Hellenes must not lose their hope of liberation by your fault. [4] On any other ground we should certainly be wrong in taking such a step; it is only for the sake of the general weal that we Lacedaemonians have any right to be forcing liberty upon those who would rather not have it. [5] For ourselves, we are far from desiring empire, but we want to overthrow the empire of others. [6] And having this end in view, we should do injustice to the majority if, while bringing independence to all, we tolerated opposition in you. Wherefore be well advised. Strive to take the lead in liberating Hellas, and lay up a treasure of undying fame. You will save your own property, and you will crown your city with glory.'