"Well, Thrasymachus said, have you never heard that forms of government differ; there are tyrannies, and there are democracies, and there are aristocracies?
Yes, I know. (Socrates)
And the government is the ruling power in each state?
Certainly.
And the different forms of government make laws democratical, aristocratical, tyrannical, with a view to their several interests; and these laws, which are made by them for their own interests, are the justice which they deliver to their subjects, and him who transgresses them they punish as a breaker of the law, and unjust. And that is what I mean when I say that in all states there is the same principle of justice, which is the interest of the government; and as the government must be supposed to have power, the only reasonable conclusion is, that everywhere there is one principle of justice, which is the interest of the stronger. "
The Republic by Plato