Sigmund Freud was well aware that his theories were controversial. "What progress we are making," he commented in 1933. "In the Middle Ages they would have burned me. Now they are content with burning my books."
As it happened, four years later the new authorities in Vienna weren't content with just burning his books and Freud had to flee into exile in London. The Nazis had annexed Austria and as a Jew there was a very real threat to his life.
Freud's books might not be burned anymore, but his work has remained controversial. However, research published in Science earlier this month suggests for the first time that there is a biological basis for one of Freud's central ideas. Could we have a Freudian renaissance in the 21st century?