An unusual case study by Sigmund Freud, in that the subject was a young child and the boy's parents did all of the "treatment." Freud had no direct psychotherapeutic contact with Little Hans.

Little Hans had developed a phobia about cart horses, which Freud attributed to a developmentally appropriate Oedipal conflict leading to castration anxiety.

Freud's course of action, and I am not making this up, was to counsel the little boy's mother to threaten to cut off her son's penis.