A Definite Answer?

As I read Book 1 of The Republic, I start to agree with Glaucon and Adeimantus in that people do right only for their benefit, but I am unsure about if this applies to justice. Each human has a different aptitude, and we keep with this skill. Socrates would agree with this, as it seems evident that he would say that each human has a certain function that can be used for a specific purpose. However, I am not so sure that Socrates would agree that people only do such things in the interest of themselves, because after all, he criticized Thrasymachus’s thought of self-interest, in which self-interest does not always come into play with one’s “functions”. I do not specifically believe that justice is just a matter of convenience, but I agree that it does factor into it. Justice, I believe, is more about truth and morals, which fall into a subjective category: justice is keeping with and following the morals of humans, but this is entirely what each of us thinks. Therefore, I do not think that there is a “correct” definition of justice, because so far, in our time, justice is only what we as humans believe is correct.