I'm thinking it might start with their algorithm for finding improbable phrases. They serve as a kind of a word-based fingerprint for a book and probably make s

I'm thinking it might start with their algorithm for finding improbable phrases. They serve as a kind of a word-based fingerprint for a book and probably make searching on over-specific queries like this one a lot easier. http://www.amazon.com/gp/search-inside/sipshelp.html http://www.amazon.com/gp/search-inside/sipshelp.html