revenge is a very dangerous motive. it allows a man to be the judge in his own case, which is exactly what the law tries to prevent. Moreover it is usually an excessive motive; it seeks to inflict more punishment than is desirable. Torture, for example, should not be punished by torture, but the man maddened by lust for vengeance will think a painless death too good for the object of his hate. Moreover, and it is here that Spinoza is in the right - a life dominated by single passion is a narrow life, incompatible with every kind of wisdom. Revenge as such is therefore not the best reaction to injury.p. 579.

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