Republic by Plato. The book puzzled me already by the first pages especially by the discussion on what a just man is. I disagree heavily on what Plato said, especially when he alluded that a just man shouldn’t not partake in a bad deed even when it’s in the defense of justice otherwise according to him even if you are just partaking in a bad deed for the sake of what is good it makes you bad as well, he also thought that a just man cannot define and say who a bad man is which is ludicrous but still understandable in the same sense