While Socrates discuss with Glaucon about just and unjust, Glaucon told a story about the ring of the Gyges. The story is a about a man named Gyges, he was a shepherd in Lydia. One day there was earthquake, and it broke open the ground and created a chasm. Gyges went into the cave, and he discovered there was a corpse, who wore a golden ring. Gyes took the ring, later he discovered the ring has the power to let him became invisible by adjusting it. He then became one of the messengers who sent report to the king. After discovered the power, he used his power to seduce the queen and with the help of the queen, he murdered the king, and became the king of Lydia himself.
Before Glaucon told the story, Socrates was discussing the problem with Thrasymachus. Which Thyrasymachus held an opinion of justice is advantageous for the stronger. He gave an example of the rulers that “each rulers declares that what is just for its subjects is what is advantageous for itself- the ruler- and it punishes anyone who deviates from this as lawless and unjust”(Public338e). After he stated his view, Socrates asked him if just is subjects must obey whatever laws the rulers make, and what if rulers made mistakes? And they order their subjects to do things that are disadvantageous to them. So in another words, in Thrasymachus opinion, “what is advantageous for the stronger is no more just than what is not advantageous”(Public340b). While everyone was questioning Thrasymachus, he