What books would you recommend that someone has to read in their lifetime?

I have read probably hundreds of books in my life and can say with absolute certainty that there is only one book that is essential reading: The ragged trousered philanthropist by Robert Tressel. I'll be surprised if you can find it, it argues that greed might not be the best foundation upon which to build society. There are many many very good books 'out there' but this one will change your life for the better in ways that you can actually develop.