Freud’s CouchAs part of his “talking cure,” Austrian neurologist Sigmund Freud invited neurotic patients to lie back on a couch and speak about their dreams and innermost thoughts. This photo shows Freud’s famous couch in his office in Vienna. His theories about the unconscious and instinctual motivation of human behavior cast doubt on Enlightenment ideals of rationalism and progress. (© Peter Aprahamian/CORBIS)