From the Introduction:

It should always be with some misgivings that an editor presents to the public materials which an author has discarded. By returning the materials to his files, the author has voted against publication. By resurrecting them, the editor risks exposing the author to the adverse criticism which he wished to avoid. But, at the same time, the resurrection serves a valuable purpose by making available indispensable evidence to be used by those seeking to understand the creative process. It is because they serve such a purpose that the texts published in this volume have been salvaged from Mark Twain's files. Indeed, they are doubly valuable because they aid in dispelling a myth about his own creative process which Twain himself did much to establish.

 

In several instances Twain gave the impression that for him plotting a novel was a rather simple affair. . . . But in actuality, as the texts published in this volume illustrate, he experienced much more trouble than this statement would suggest in delimiting his fictional world, establishing its nature, and maintaining control over the characters placed therin.