Revenge loses sight of the end in the means, but it's end is not wholly bad - it wants the evil of the bad man to be to him what it is to everyone else. This is proved by the fact that the avenger wants the guilty party not merely to suffer, but to suffer at his hands, and to know it, and to know why. Hence the impulse to taunt the guilty man with his crime at the moment of taking vengeance: hence, too, such natural expressions as 'I wonder how he'd like it if the same thing were done to him' or 'I'll teach him'. For the same reason when we are going to abuse a man in words we say we are going to 'let him know what we think of him'.
C.S. Lewis
revenge, vengeance