Historically, dust jackets are a new concern for authors; you don't see them much before the 1920s. And is a strange name for this contrivance, as if books had anything to fear from dust. If you store a book properly, standing up, then the jacket doesn't cover the one part of the book that is actually exposed to dust, which is the top of the pages. So a dust jacket is no such thing at all; it is really a sort of advertising wrapper, like the brown paper sheath on a Hershey's bar. On this wrapper goes the manufacturer's name, the ingredients--some blithering about unforgettable characters or gemlike prose or gripping narrative--and a brief summation of who does what to whom in our gripping, unforgettable, gemlike object.