you know when the novel is done when —

— the characters live both on the page and off; they are forever part of you now;

— the book rises and falls, not just with character and plot, but with all the other things that make a life, that make a story, that write a song;

— you slow down because you don't want to leave the world you have finally entered, for you are comfortable there, at peace there, no longer in the throes of struggle;

— you write your acknowledgments and you can see just how those who helped you helped —by asking questions, by reading with care, by saying, You can;

— you feel not just glad but somehow emboldened for the next time (for there will be a next time) that you chose to see this story through to its end. You learned (again) how hard this is. You learn that lesson every time.