I've been chewing over that question still further since seeing the Alice in Wonderland exhibit at the Tate Liverpool. One of the (physically) central rooms of the show is audible dominated by the persistent advancing of an automated slide projector. In a room of hard walls, it's a real sound barrier to hearing much else from any distance.
Also in that room, on a large grey carpet, were a series of abstracted pieces of solid furniture: a bright red square representation on a fireplace; different sizes of benches and tables, whose abstractions of decorate turnings showed they might well be Victorian in inspiration. On top of these were a series of A4-sized cardboard boxes, each partially-filled with photocopies of parts and pieces of books.
Over the sound of the slide projector, I couldn't hear what the guard had explained to the other person in that room at the time. I had to wait for my own explanation. She told me that the work was conceived as interactive with visitors. Entitled "The Never Ending Book", by Allen Ruppersberg, visitors were invited to take away with them their own curated selection of up to five A4 sheets from any - or a selection of - the boxes. This selection would be a book in its own right, the piles producing, therefore, an unending book.
Really? I would argue it was the photocopies which produced the "never ending" "book" of the installation. The selection of sheets was pre-selected by the artist, and unifying those sheets in a cardboard box is far closer to binding than the mere act of selecting sheets and carrying them - looseleaf, unbound, scrollable - away.
But ultimately, is any of it really a book, in anything more than title and source material for the photocopies?
The act of browsing through the selection of photocopied pages was moderately intriguing at least, seeing what the artist had selected in fragments of poetry or tables of contents or full-color photocopies of parts of covers or the handwritten dedication of what looked - from a fragment of copyright - like a Wellesley year book. I took four sheets with vague intentions of collage and, bookless, went on to a room undominated by the advancing of a slide projector.