But there are problems with it, too.
The first problem I see is that different people skip different things. I know many people -- including writers -- who swear they never read a preface or introduction or acknowledgements. I'm one of those people who does read all of the above. I like knowing what's behind a book. Knowing who the author thanks and how they do the thanking gives some insight into the author's personality and life, and I'm enough of a voyeur to enjoy that. I also like to learn more about why the book came to be, and that information is often framed in an introduction. One argument against those "peripheral" materials is that the book should speak for itself. I agree. I just think that "the book" is everything between the covers. Come to think of it, the front and back covers count, too.
Even if we stick to the main part of the book, though, the "skippable" parts vary with the reader. My husband skipped the long passages on church history and semiotics in Umberto Eco's The Name of the Rose. As a student of folklore/linguistics/anthropology, I read and reread Eco's novelistic treatment of signs and symbols, and found the convoluted politics of the medieval church fascinating. But then I read "the whale chapter" in Moby Dick. Several times.
Really, if we think about it, we can't avoid writing the parts that people skip because (and I know this is hard for the writers among you to read) some people will skip everything we write. I have personally skipped every word of quite a few books that simply didn't interest me. I've skipped everything past the first whatever number of pages or chapters in books I found boring or offensive or poorly written or.... I've skipped chapters that didn't interest me. Haven't you?
But back to Leonard. I think the real wisdom in the pearl I've quoted is the directive to consider what we include, to be sure it matters in the context of the story, the essay, the poem, the play. As writers, we have to exercise our critical muscles on our own work, and we have to be willing sometimes to delete. We also have to be willing to stand up for the parts we believe should be there, even if some readers skip them.
What parts do you skip when you read? What do you read that other people say they skip?