Ask HN: if you could only read one book, which would it be?

Pre-modern age, reading was a very narrow, deep activity. Books were rare, and a lucky person owned one, maybe two. These days, information is cheap, and most people only read a book once. I personally have a Kindle with hundreds of books on it, most of which I won't read again.

So, if you had to pick one book to read hundreds of times, to know word-for-word from front-to-back, what would it be?