The contributions of psycho-analysts to psychiatry may be divided into three groups which fall roughly into three periods. The first period ranges from 1893 to 1914, the second from 1914 to 1923, the third from 1923 till the present. The first group is characterized by a simplicity not found in later work, and may be summarized by saying that the psychoses were viewed from the aspect of libido development; stress is laid on fixation points, on defence mechanisms, on the aims of the sexual instinct and on