A man like me cannot live without a hobby-horse, a consuming passion—in Schiller's words a tyrant. I have found my tyrant, and in his service I know no limits. My tyrant is psychology. —Sigmund Freud, 1895, in a letter to W. Fliess
quoted in "Counseling and Psychotherapy Theories in Context and Practice: Skills, Strategies, and Techniques (Sommers-Flanagan, John;Sommers-Flanagan, Rita)"