I just read this fantastic quote by Anne Lamott (she has a wonderful writing book, called Bird by Bird, that I used to assign my students):
Writing is about hypnotizing yourself into believing in yourself, getting some work done, then un-hypnotizing yourself and going over the material coldly.
I'm not even sure this is the way Ms. Lamott meant it, but I interpret it this way (regarding the writing/editing process): There's an emotion, a raw quality that must be inserted into a rough draft. It's important to "feel" the characters, what they're going through - to empathize with them, so that the reader will, too.
But that emotion really does have to be squelched when it comes to the editing process. We have to look at it "cold." We need to be brutal about slashing words and phrases, even storylines and characters that do not belong. It's tough to do that. Sometimes, it feels impossible. I'm experiencing that right now, as I edit Book 2. I'm trimming the fat, cutting or rearranging whole scenes or pages of dialogue, taking out and adding in. This is the time when emotion can't factor into the editing decisions (at least, not to a great degree). I think we have to look at it "coldly," with distance. An editor's eye. And back to the rough draft - the opposite is true. If we look at a rough draft coldly, we remove its heart, its emotion.
In terms of writing, I think there's a time to be warm, and a time to be cold.