The Einstein of SexMore than a century ago, Dr. Magnus Hirschfeld, dubbed the "Einstein of Sex," grew famous (and infamous) for his liberating theory of sexual relativity. Today, he's been largely forgotten. Journalist Daniel Brook retraces Hirschfeld's rollicking life and reinvigorates his legacy, recovering one of the great visionaries of the twentieth century. In an era when gay sex was a crime and gender roles rigid, Hirschfeld taught that each of us is their own