Austrian physician Josef Breuer (1842-1925) collaborated with Freud on the work which originated many aspects of psychoanalysis, their Studies in Hysteria (1895). The book's foundation was Breuer's case study of a young patient he called 'Anna O.', who presented with various mood disorders and physical symptoms which were then considered hallmarks of hysteria.
The 'talking cure' process which Anna and Breuer developed in their sessions anticipated several key elements of Freudian analysis, including the concept of disturbing memories being at the root of nervous illness. After their eventual estrangement Breuer would come to be depicted by Freud and his followers as something of a stooge, representing the stunned resistance to his theories which supposedly proved their truth.
Online edition of Freud and Breuer's 'Studies in Hysteria', as translated by A. A. Brill, (1937)