This was one of just a few case studies which Freud published. In his introduction to the case, he had in the years before the case been encouraging his friends and associates, including Graf's parents, to collect observations on the sexual life of children in order to help him develop his theory of infantile sexuality. Thus Max Graf had been sending notes about his child's development to Freud before Herbert's fear of horses emerged. As "Little Hans", he was the subject of Freud's early but extensive study of castration anxiety and the Oedipus complex. Freud saw Herbert only once and did not analyze the child, but rather supervised the child's father, who carried out the analysis and sent extensive notes to Freud. In the published version, Herbert's father's account is abridged and punctuated by Freud's comments.