Athenians: Aim at what is feasible, holding in view the real sentiments of us both;
 since you know as well as we do that right, as the world goes, is only 
in question between equals in power, while the strong do what they can 
and the weak suffer what they must....
Melians: As we think, at any rate, it is expedient —we speak as we are 
obliged, since you enjoin us to let right alone and talk only of 
interest— that you should not destroy what is our common protection, the
 privilege of being allowed in danger to invoke what is fair and right, 
and even to profit by arguments not strictly valid if they can be got to
 pass current....
Athenians:  Of the gods we believe, and of men we know, that by a necessary law of their nature they rule wherever they can.....  It is certain that those who do not yield to their equals, who keep 
terms with their superiors, and are moderate towards their inferiors, 
on the whole succeed best.
  Thucydides (Book Five), 
The History of the Peloponnesian War