Ever since I finished D'Agata's About a Mountain, and I've been thinking about the book-length essay. Mainly, I've been wondering if such a thing exists.
About a Mountain reads like a series of well-linked essays (keeping the momentum of shorter work while tackling multiple, broad themes that seem wider in scope than what can be done in 20 pages), but I don't know if I can consider it an essay in and of itself. Another example of this is found in Eula Biss's The Balloonists, which reads like a 120 page braided, personal essay. With that said, there are bigger organization principles that amount to chapters, so would we call this a memoir, rather than personal essay? Is there a difference? Does it even matter?
I'm not making any real conclusions here, but I would like to try and generate some discussion here: How do we (or don't we) define the book-length essay? Other good examples out there?