Going through copyedits is rather like putting your book under a magnifying glass, though. Somehow I forget this each time, until they arrive. But suddenly all the small flaws jump out at you, and seem large, and it becomes hard to see the book clearly as a whole.
I'll take it on faith that the whole still holds together, though--just as I have every other time--and resist the urge to seize hold of the manuscript and rewrite it from the ground up.
Because at this stage of the process, that would be bad. :-) Also because I'd like to maintain the illusion that I'm of the sane species of writer.