In the Foreword to the present revised edition which first appeared in 1956, Jung says: '...it was the explosion of all those psychic contents which could find no room, no breathing space, in the constricting atmosphere of Freudian psychology... It was an attempt, only partially successful, to create a wider setting for medical psychology and to bring the whole of the psychic phenomena within its purview.'
For this edition, appearing ten years after the first, bibliographical citations and entries have been revised in the light of subsequent publications in the Collected Works and in the standard edition of Freud's works, some translations have been substituted in quotations, and other essential corrections have been made, but there have been no changes of substance in the text.