From Guy Claxton, The Wayward Mind: An Intimate History of the Unconscious, 2005:
Lancelot Law Whyte [Unconscious Before Freud, 1967] has demonstrated beyond doubt that ‘by 1870-1880 the general conception of the unconscious mind was a European commonplace, and many special applications of this general idea had been vigorously discussed for several decades.’ Fifty thousand copies of von Hartmann’s book on the unconscious were sold in Europe in the 1870s, and it was as widely discussed as, say, the works of Richard Dawkins or Stephen Jay Gould are today. During the two hundred years before Freud dozens of thinkers, possibly as many as a hundred, had published a wide variety of ideas about unconscious processes. Yet shortly before his seventieth birthday, Freud was still insisting that ‘the overwhelming majority of philosophers regard as mental only the phenomena of consciousness’. Whether his amnesia for all the sources that were saying otherwise was feigned, deliberate or itself unconscious, we can only surmise.
Though Freud, in the end, may have added few if any truly novel ingredients to our understanding of the unconscious, he drew a number of strands of thought together, and packaged them in a way that was at once accessible, salacious and seemingly scientific. He appealed to people with tabloid interests and broadsheet intellects, and gave a repressed European society an impersonal language with which to talk about the desires and failings which their upbringings had taught them to hide.