Some societies believe that the punishment in revenge should be more than the original injury. For example a poll of over 1800 Americans showed that about 40% would support the death penalty for child rape.
Somebody once wrote, "Revenge is a dish that has to be eaten cold." Hot as you are, you're liable to end up with indigestion.
The desire for revenge keeps one's wounds open.
"Crom|Crom, I have never prayed to you before, I have no tongue for it. No one, not even you, will remember if we were good men or bad, why we fought or how we died. No, all that matters, is that few stood against many. That's what's important. Valor pleases you, Crom, so grant me one request: grant me revenge! And if you do not listen, then to hell with you!"
"Revenge is the prime ingredient in the fountain of youth."
"Revenge is like a poison. It can take you over, before you know it, it had turn you into something ugly."
"If you wish for revenge, an equally hard blow will be dealt back to yourself."
"In certain, extreme situations, the law is inadequate. In order to shame its inadequacy, it is necessary to act outside the law. To pursue - natural justice. This is not vengeance. Revenge is not a valid motive, it's an emotional response. No, not vengeance. Punishment."