Like many voracious readers, I tend to gather books. Every couple of years I thin them down, donating to area libraries and such. I've moved a couple of times and had to thin down extra at those times.
It's hard ...
So I can only imagine the struggle of having to pick just one book. It's like the interview question, if you were stranded on a deserted island with just one book, what would it be? Um ...
I don't even know where to begin to narrow down my bookshelves to just one book. Most of my favorites are parts of trilogies or small series with set ending points.
What I do know is without authors, there would be no new books. The lose of any work of art, be it a painting , a symphony, or a book, is a detriment to the world. Yet the lose of creativity would be much much worse.
While we may never see a repeat of the abilities of some of the masters, new ones will arise in time, so long as we nurture the crative spark within us. So rather than risk all to save one book, which would probably by the one I happened to grab off of my shelf in a moment of panic rather than one selected with deliberation, I would let them be taken.
I would then commit my life to recreating what I could, and writing new stories, hoping that it would help keep creativity alive within the human condition, so that future generations will be able to enjoy their own masters of the arts.