Rapaport's approach to psychological testing revolutionized clinical psychology. His first manual was widely used by psychologists during World War II, and in its final form became the two-volume Diagnostic Psychological Testing (1945–46), which remained widely used by psychologists into the 1980s (Fritsch, 2013). Rapaport also brought psychoanalytic theory into the 20th century through his lectures and writing. His lecturing style “was extraordinary and to some intimidating, especially to those accustomed to gentility in scientific discourse. He discussed abstract metapsychology with the fervor of a political orator and the thunder of a Hebrew prophet.” (Gill, 1961, p. 757)