Revenge vs. Vengeance
Definition of Revenge: retaliation for an offence or injury
Definition of Vengeance: punishment inflicted or retribution exacted for wrong to oneself

So I suppose that in a way Samuel Johnson was quite right when he said; "Revenge is the act of passion, vengeance is an act of justice" and so was Robert F. Kennedy when he said; "Don't get mad, get even" which is a more popular way of saying the exact same thing.

In essence both the quotes are telling you to put aside your feelings and instead let your logic guide you to emotional satisfaction/retribution. Not an easy feat for a human being, though, since human beings are mostly prone to let themselves be guided by feelings and instinct.

There is a certain person whom I have hated and wished revenge upon at a certain time in my life. I just chatted with that certain person today, which is probably why I am now writing this. This person spurned me after 8 years of being together on and off and for a long time I had the hardest time coping with feelings of hatred and bitterness towards that person.

Then came The Corrs with their CD "Forgiven, Not Forgotten" and after hearing that particular melody "Forgiven Not Forgotten", it dawned on me that I could spend a whole lifetime hating this certain person - thereby wasting my life and energy on negative thoughts.
Then I came across a quote by Francis Bacon who said; "In taking revenge, a man is but even with his enemy; but in passing it over, he is superior" and hence made the decision that although it would be hard to forget this certain person, I would do my best to make it so and get on with my life - and make it a good life.

I succeeded in getting on with my life and it definitely has become a good one and on top of that, today I realized that this certain person no longer mattered to me or made anything move inside me. This certain person who had once been the center of my life, the beginning and end of everything, was an absolute non-entity. Oh, I enjoyed chatting with this certain person, even when the conversation turned towards more dangerous topics, but I felt no stirrings of the heated passions of bygone times. It was enjoyable simply because this certain person is intelligent and witty and has a great sense of humor.
And realizing that also made me realize that unknowingly I had actually had the best vengeance of all; this certain person had seized to be of any importance to me.