This volume is a treatise on mystical theology in agreement with the principles of St. Teresa set forth by the Carmelite Congress of 1923 at Madrid. This work is based on a course of lectures on ascetic and mystical theology which set forth the traditional teaching of the Church and at the same time directed special attention to present day questions raised by the progress of contemporary science. Mgr. Farges presented these lectures at the University Seminary at Angers for seven years, and at that time the course was a novelty. Today the need of these studies for higher education of the clergy and for Christian apologists is universally admitted. It is this course of mystical theology which the author decided to publish in the present volume.