Republic Book 1 EP11 What is Justice?

It is in Book 1 of Plato's dialogue Republic that political philosophy begins. The character Socrates begins by asking a pivotal question "What is justice?" He receives and disposes of two weak definitions but is quickly confronted by Thrasymachus who ties the concept of justice to whatever is to the advantage of the ruler. Socrates attempts to refute this definition but believes that his refutation is weak. He says, at the end of the chapter, that "the result of the discussion, as far as I am concerned, is that I know nothing [about justice]."