Is a book just words? I think it is easy to argue the case that a book goes far beyond this. The obvious approach would be that the words create meaning. Authors will make different selections of words and that contributes too – a cheap potboiler might deliberately stick to a limited vocabulary while, personally, I loved the novels of PD James, which always had one or two treats to send me rummaging for my dictionary.
Another approach though would be to play the punctuation card. As well as words, an author has to use punctuation to express themselves; a misplaced comma can entirely alter what is conveyed (as in the case of that rogue panda who eats, shoots and leaves rather than eating shoots and leaves!). I recently came across a fascinating exploration of novels with all the pesky letters stripped out and only the punctuation left behind. Obviously you can’t glean much meaning from that but you can get a perspective on authorial style that is normally obscured.
I wonder if that could be worked back as a conscious writing exercise or even just a divering puzzle? Here are the bones; now flesh out into a story or essay but adding back words of your choice?