6o To desire to revenge and then to carry out revenge means to be the victim of a vehement attack of fever which
then, however, passes: but to desire to revenge without possessing the strength and courage to carry out revenge means to carry about a chronic illness, a poisoning of body and soul. Morality, which looks only at intentions, assesses both cases equally; in the ordinary way the former case is assessed as being the worse (on account of the evil consequences which the act of revenge will perhaps produce). Both evaluations are short­ sighted. From Human All Too Human 

Reading philosophy can be challenging. Reading Nietzsche can be challenging, too. There are many reasons why I read a lot of Nietzsche. First of all, he just spoke to me; it’s like we enjoy the same music and stick with each other to enjoy it; there is no higher philosophical reason for it. I didn’t know anything about philosophy when I started reading it, so I could not be attracted to anyone’s philosophy. One thing that I still appreciate is that Nietzsche, for the most part, asks questions through all kinds of answers. He is not trying to tell you how the world works through elaborate systems spanning hundreds of pages. He writes aphorisms from one sentence to a couple of pages that are all loosely connected with the ones before and after. You can read his books from beginning to end but you can also open one and just read one of the aphorisms and think about it. 

Interpretation

Italic = Nietzsche’s text Bolt = my interpretation and rewording 

To desire to revenge and then to carry out revenge means to be the victim of a vehement attack of fever which then, however, passes: but to desire to revenge without possessing the strength and courage to carry out revenge means to carry about a chronic illness, a poisoning of body and soul. If you act directly on the urge to take revenge, that feeling that comes over you and clouds your judgment like a fever does, you will be freed of that feeling to take revenge. If you don’t act on that urge but take it with you, it might consume you from the inside out. Morality, which looks only at intentions, assesses both cases equally; Morality for Nietzsche is often closely related to Christianity and, in this case, the thought of revenge or the act of revenge is the same for an all-knowing God. in the ordinary way the former case is assessed as being the worse (on account of the evil consequences which the act of revenge will perhaps produce). The ordinary way is how secular society judges you, and acting on an urge is worse than not acting on it. Both evaluations are short­ sighted. And like Nietzsche tends to do, he throws a spanner in the works and forces you to think. The moralistic view is short sighted because of the judgment of an urge but the “ordinary way” because of the outcome of acting on that urge? In this case, it might help to read the aphorism before this one because, at this moment (late in the evening after a day’s work outside), I don’t see the other cause where the “short sighted(nes)” alludes to. Maybe he wants to tell us that it is, in both cases, a disease that makes us feel like taking revenge, or better said, we don’t choose to feel what we feel, and we don’t choose how we react; we react. Our circumstances determine how we react; there is no I that acts.