In the Preface, the author, posing as a character-version of himself, introduces the story and says that since people are so interested in reading fiction, they may not think the tale they're about to read is true.
He addresses the fact that Moll won't use her true name in the story and explains he's only changed it a little from the original.
Apparently, it was pretty tough to get Moll's story into acceptable, readable shape, as it was kind of vulgar originally. However, he's worked really hard to make sure that it won't offend anybody who reads it now, and that it should seem moral and interesting to readers. Oh now this is getting interesting…
In order to keep it true to life, the author had to describe some of the "wicked" (5) parts as they really happened. He apologizes that the parts where Moll repents for her sins may not seem quite as interesting as the sinning parts. Ha.
He encourages readers to learn more from the end of the story than from the events within it, and gives examples of the events Moll endures to support his idea. And he compares his book to plays and says that, just like them, his book may be "lively" but it is also "useful" (11).
After all, every character in the book gets his or her just rewards in the end, and each element of the book has something to teach the reader – the scenes in which Moll acts like a criminal, for example, instruct readers on how to look out for thieves. Added bonus, indeed.
He says there are many examples throughout the book of its usefulness in that way, and because of it, the book simply must be published. Hmm, funny how that turned out.
Alluding to two other books and life stories that influenced what happened to Moll, the author mentions the lives of her governess and her criminal husband. The author says he doesn't have enough time to talk about them right here, so he's not sure how much they'll show up in the book itself.
He apologizes that this isn't the complete life story of Moll, because a complete life story only ends with someone's death, and that isn't included here. From reports of Moll's husband's life, though, we can get a better idea of it.
And finally, he says that by the "last scene" (22) Moll's story is becoming less and less eloquent, so that makes it a good place to draw her story to a close. Well that sounds suspiciously convenient. This author has a wicked sense of humor, that's for sure.