Quote Originally Posted by sharrukin
"When we see one man oppressed or injured by another, the sympathy which we feel with the distress of the sufferer seems to serve only to animate our fellow-feeling with his resentment against the offender. We are rejoiced to see him attack his adversary in his turn, and are eager and ready to assist him whenever he exerts himself for defence, or even for vengeance within a certain degree." -Adam Smith

This is vengeance and retribution and it is why we despise the Nazi camp guard and lend our sympathy to the inmate of such places. Anger is the sentiment aroused by the sight of injustice, and is therefore intimately connected with justice. Should we not exact retribution from those who wrong us? Should we not act as defenders for those who cannot defend themselves?

Justice makes a virtue of controlled vengeance.
Well said.