There you are, working on the new WIP. You've just gotten the check for your manuscript's acceptance. The world seems like a brighter place. Birds are singing in the trees and the tune they're singing is you favorite song. Desserts have less calories just because the weight of the world is no longer on your shoulders...
And then you get the package. Maybe it's a yellow-orange DHL package. Maybe it's FedEx or UPS, but you know that contained within is a force that will execute those singing avians (or at least alter their tune to something horrid and off-key). It will dim the light of the universe by no less than twenty percent and almost certainly cause you to lose sleep (possibly hair) and it will absolutely cause those vanished calories to return... with reinforcements.
It's your manuscript. Your darling little perfect manuscript. Only now it has been exposed to the light of truth. Now, it has been copyedited and this, my friend, this is the last chance you'll have to make things right.
All the accidentally repeated words, the logical errors, the jumps in scene... the flaws you thought you'd polished away, stand out in sharp relief, exposed in tones of brilliant red and blue. Now, there may even be questions in the margins. Good questions. Vital questions, that must be answered. There is hope, though.
Hope comes in the shape of a green pencil and time. Maybe you get a week. Maybe you get two or three, but the time is vital. All questions must answered and all plot points fixed, because after the green pencil is laid to rest and the manuscript is sent back to your editor, your final opportunity to make substantial changes to your baby, to alter its literary DNA in such a way that it evolves into the best book it can be... is gone.
Oh, you'll see your book again one last time and you'll be able to correct typos. You might even be allowed to rewrite a sentence here or there, but that new chapter that you always meant to write is unlikely to ever grace the page unless you fix it now.
Or am I the only one who feels that way about copyedits?