FAQ #Something: Do I have to finish the manuscript before I send you a query letter or the first two chapters?

I’ve gone both ways on this question in the past, but I thought about it a little more over the last week, and I’ve decided: Yes. Yes, you do. Because, as Maxwell Perkins said, "You can't know a book until you come to the end of it, and then all the rest must be modified to fit that"; and because what you want to send, and what I want to see, is your very best work—a draft you’ve completed, thought about, reread, tweaked, polished, perhaps had other people read, and in general taken to the point where you’ve done everything you can with it, and you’re ready for an editor’s (or agent's) opinion or advice. And no matter how assiduously you plan out your writing, I don’t think you can know what your very best work is until you’ve actually written it. So yes: Finish the manuscript first.