The term “psychoanalysis” has a triple usage. First, it describes a connected body of observations about unconscious mental processes, systematically classified and more or less colligated and brought under general laws. This first meaning places psychoanalysis among the sciences, but a difficulty at once arises; for the phenomena with which psychoanalysis is concerned, and the methods used to study them, are so different from those upon which our tradition of science was first based that the question arises whether it is science at all.