Simple desires beget simple utopias. If you’re hungry, you dream of a lavish banquet. If you’re cold, you dream of a toasty fire. Faced with mounting infirmities, you dream of eternal youth. All of these desires are reflected in the old utopias, conceived when life was still nasty, brutish, and short. “The earth produced nothing fearful, no diseases,” fantasized the Greek poet Telecides in the fifth century B.C., and if anything was needed, it would simply appear. “Every creek bed flowed with wine … Fish would come into your house, grill themselves, and then lie down on your table.”