The Republic of Plato

Socrates' young companions, Glaucon and Adeimantus, continue the argument of Thrasymachus for the sake of furthering the discussion. Glaucon gives a lecture in which he argues first that the origin of justice was in social contracts aimed at preventing one from suffering injustice and being unable to take revenge, second that all those who practice justice do so unwillingly and out of fear of punishment, and third that the life of the unjust man is far more blessed than that of the just man. Glaucon would like Socrates to prove that justice is not only desirable, but that it belongs to the highest class of desirable things: those desired both for their own sake and their consequences. To demonstrate the problem, he tells the story of Gyges, who with the help of a ring that turns him invisible achieves great advantages for himself by committing injustices.