When we realize our collective concept of justice is without a soul, heartless and cold, we will understand why peace is necessary and how to achieve it. The only difficulty is that realization is rarely achieved collectively, and the awakened individual is left without support, accused of undermining justice by calling for mercy. Perhaps there is a critical mass factor involved.
The right to defend oneself is innate and instinctual, and not evil. But the right to punish after the immediate danger has passed is more a cultural construction, feeding on the animal instinct for revenge which no longer functions as a balancing impulse. We encourage victims to get revenge through impersonal systems that do not heal because they are as inhuman as our conceptualization of justice.