Douglas R. Hofstadter and Daniel C. Dennett
Publisher: Bantam Books (1982)

there is a world -- a branch of the universal wave function – in which you didn’t make that stupid mistake you now regret so much. Aren’t you jealous? But how can you be jealous of your self? Besides which, there’s another world in which you made yet stupider mistakes, and are jealous of this very you, here and now in this world!