In the history there are books that have influenced man's knowledge:
Charles Darwin's Origins of Species ...
Thoreau's Walden ....
and now ......
The Hitchhiker's Guide to the Galaxy is a five book trilogy (hint) is an intelligent blend of wacky humor in the British Tradition of Monty Python and thoughtful science fiction. It started as a BBC radio series, and evolved into the books, audio tapes, BBC TV series (with second series coming), a movie, and some of the greatest quotes and thoughts !
Great Links below.
THE AUTHOR - DOUGLAS NOEL ADAMS
Learn why 42 is the answer to life, the universe and everything
Thought the ultimate 42 list -