Once aroused, the urge to violence triggers certain physical changes that prepare men’s bodies for battle. This set toward violence lingers on; it should not be regarded as a simple reflex that ceases with the removal of the initial stimulus… it is more difficult to quell an impulse toward violence than to rouse it, especially within the normal framework of social behavior.
Violence is frequently called irrational. It has its reasons, however, and can marshal some rather convincing ones when the need arises. Yet these reasons cannot be taken seriously, no matter how valid they may appear. Violence itself will discard them if the initial object remains persistently out of reach and continues to provoke hostility. When unappeased, violence seeks and always finds a surrogate victim. The creature that excited its fury is abruptly replaced by another, chosen only because it is vulnerable and close at hand.
Girard, Rene. Violence and the Sacred. Johns Hopkins University Press. p.2.
Commentary that has become very practical in our country regarding race.