How do you know when your novel is finished?

I've been working on my first novel for over 5 years. Admittedly, I was also working on several short stories and flash fiction pieces...and sneakily squeezing in a Ph. D. in molecular geobiology on the side. My original goal was to finish my book by January 1st, 2007. Then the deadline was moved to January 1st, 2008. Now, it's January 7, 2009, and I can officially say, I'm DONE! But, am I really? What does a finished novel actually look like anyway?

It wasn't that I got to The End. No, I had done that a couple of years ago. I've had several complete drafts, with plots and characters and conflicts and beginnings and middles and ends. But, I always felt like there was more I could do to make the book better, scenes I could improve, emotions I could clarify by cleverly showing and not telling. Although I had several kind souls who read these early drafts, I never fully felt like the book was ready for human consumption, not really. What I had, in my opinion, were prototypes, novel drafts made of styrofoam so that readers could get the general idea without actually experiencing the real thing.

But, somehow, with this latest draft (#39, but counting really is pointless) I felt like I had something different. I felt like I could let people read the hundreds of pages and see, not what the book could be, but what it actually was. So, naturally, I gave it out to two of my best readers as soon as I could. I also told about a dozen other people, at least two of them admitting that they thought I would NEVER finish the thing, or that if I did, I would never be happy with it. (I appreciate the honesty.) And, then...I couldn't sleep. Because, wasn't the beginning just a little too flashy? And, did I really pace myself in the pineapple stand scene? The fact is, I don't know. And, I probably won't know for a long time coming. I'm so close to my book that I can't really tell if it's done or not.

Luckily, I have my friends. Honest friends. People may donate organs to you on a whim, but the real test of friendship is whether or not they will read through a rough draft of your novel and tell you the truth about what they think of it. I'm probably one of the many writers who will never be fully content with this beast I call my novel. I'll send it out to friends and mentors, and eventually the agents who I truly, truly respect even if they scare me, but there will always be those words and sentences and paragraphs that I'm not fully happy with. So, faced with this frustrating obstacle -- myself -- what can I do to move on and at least function enough so that I don't carry my dinner plate to the bathroom sink again? I'm working on my second novel to clear my head. I'm researching submission guidelines and query letter advice. And, I'm waiting for opinions. Chances are, the people who are reading my book will tell me I need to fix it, probably in several places. They are better writers than I am, so I trust them to give me sound advice. I'll work on it some more. I'll get more opinions. And, eventually, I'll carefully place it into a box and send it off to the professionals with the hope that they will care about the work and be as critical of it as I am.