The Republic by Plato Part 1 Page 40

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.

Now I understand you, I said; and whether you are right or not I will try to discover. But let me remark, that in defining justice you have yourself used the word ‘interest’ which you forbade me to use. It is true, however, that in your definition the words ‘of the stronger’ are added.

A small addition, you must allow, he said.

Great or small, never mind about that: we must first enquire whether what you are saying is the truth.