Next, Socrates reminds Thrasymachus that even thieves have to trust one another and to show it by a fair division of their ill-gotten gain. That is, they too have to practice a kind of justice; otherwise, a gang of thieves would break up and their little "state" would degenerate into disunity, chaos, unhappiness. Unjust men, at whatever level of their practicing injustice, degenerate from an assumed strength to weakness.
Socrates' next argument advances analogies of the pruning hook, the eye, the ear, and the soul, all of which possess their several essences, what we may call their essential functions, or virtues. The eye sees, the ear hears, the pruning knife cuts well. These are their several virtues. What of man and his virtue in this instance? Man's virtue herein is his justice; it enables him to live well in harmony with others and to be happy. Only justice can bring happiness. Injustice at whatever level brings chaos, discord, unhappiness. In thus producing happiness, justice may be said to be more profitable than injustice.
At this point Thrasymachus quits the debate.
