Should you start with the introduction?

When I work with an author on the whole manuscript (versus just the nonfiction book proposal or scholarly prospectus) it involves that individual sending me sections of the book as they are written. I'm surprised how many authors start with the introduction. This may be helpful as a throat-clearing exercise, but for the most part, introductions work best when they are crafted last. Ditto first chapters, that can sometimes serve as gateways into the rest of the book. After all, an introduction should reflect a full understanding of what the book is and what it accomplishes -- yet few writers truly grasp this when they start writing. Most of the writers I've worked with (myself included) have to go through the journey of crafting the manuscript and paring/editing it down to size before we realize what sort of horse we've carved.

Or perhaps it's a bit like cupcakes. You make the little thing first, and then ice it. (Okay, I'm reaching here, but it's only 9:10 a.m. and I already want a snack.)

*Image swiped from howtoeatacupcake.net.