Thrasymachus has just stated, "Justice is nothing other than the advantage of the stronger", and is now, at the request of Socrates, clarifying his statement.

"'Don't you know that some cities are ruled by tyranny, some by a democracy, and some by an aristocracy"'
'Of Course.'
'And in each city this element is stronger, namely, the ruler"'
'Certainly.'
'And each makes laws to its own advantage. Democracy makes democratic laws, tyranny makes tyrannical laws, and so on with the others. And they declare what they have made - what is to their own advantage - to be just for their subjects, and they punish anyone who goes against this as lawless and unjust. This, then, is what I say justice is, the same in all cities, the advantage of the established rule. Since the established rule is surely stronger, anyone who reasons correctly will...