Freud's first work of applied psychoanalysis was the book on jokes (Jokes and the Relation to the Unconscious, 1905, standard edition, vol 7, London: Hogarth Press, 1906). He deduced from the cultural phenomena the whole pathway of psychic processes that had to be traversed in order to lead to its production.
Kurt Eissler in his recent paper ("Freud and the Psychoanalysis of History," J Amer Psychoanal Ass, [No. 4] 11:675 [Oct] 1963), states that the joke is the smallest cultural unit. It lent itself so beautifully to the deductive process to which Freud submitted it because it stands on the border between autoplasticity and alloplasticity; whereas most other cultural products become wholly alloplastic.
In a previous review of a book on humor (J Amer Med Coll [Oct] 1957), this reviewer stated that since the 1905 paper of Freud, little had been added to the understanding of this universal process.