Life is like riding a bicycle. To keep your balance, you must keep moving.

To Albert Einstein's consternation, his son Eduard was a big fan of Sigmund Freud. He had a portrait of the psychoanalyst hung over his bed, and at the age of 15 would often quote Freud offhand to his friends. It was no secret that Albert disapproved of his son's enthusiasm. So when Eduard fell into a brutal depression and attempted to treat himself by means of psychoanalysis, his father gently suggested a more practical approach: "How beneficial a job would be for you," Einstein wrote in the same 1930 letter to his son where this quote appears. Today, talk therapy — that contemporary descendant of Freudian analysis — is not generally understood to be in conflict with Einstein's advice. Indeed many contemporary therapists might see Einstein's encouragement that his son “keep balance” and "keep moving" as therapeutic ideas themselves.