What is the greatest book of all time?

For its impact upon Mankind and its sheer life values and wisdom and in terms of its total sales, there has been no book at all to match 'The Holy Bible' in a worldwide sense.

In terms of fictional works, the answer would depend upon what type of book.

For romance novels, with out a doubt, "Princess Bride" is the greatest book.

For fantasy, the 'Harry Potter' series. For mystery, Nancy Drew ... and so on.

For children's fairytale books, it could be any of quite some number. Certainly in terms of popularity, perhaps, Cinderella, Snow White, or even 'Goldilocks and the Three Bears'!