When will you know to stop rewriting?

...and in last place.
Tim Norris
via Compfight

“The novel never attains the level of perfection. No matter how much you rewrite and rewrite again, you will still find places in the book that don’t do exactly what you want. You will feel that some characters are hazy, and plot connections unsure. There’s a subplot that will seem to get lost and a fairly important character that will change but not as much as you might have wished. This is true for all writers in all forms. Books are not pristine mathematical equations. They are representative of humanity and therefore flawed. ‘So when will I know to stop rewriting?’ you ask. When you see the problems but, no matter how hard you try, you can’t improve on what you have. That’s it….Congratulations. You have a novel. This one is good. The  next one will be better.”