This volume contains Health; Mental Purification; The Mind World. These books explain the Sufi teachings concerning the influence of the mind on the body and the possibilities to restore rhythm and tone of a person through spiritual healing. When Health, the first book of this volume, was published in 1931 it met with great interest, for it is as rare to find a book on spiritual healing in which the advance of modern medical science is appreciated, as to find acknowledgement of spiritual healing in a medical text-book. Hazrat Inayat Khan, the Sufi mystic, has set forth in the lectures and other papers included in Health, which were originally intended only for his pupils, the basic laws, governing the divine healing power as well as several methods it application. As with all mystical knowledge, the printed word alone can never confer the power and knowledge of healing upon anyone; a guide, a teacher is essential; but the reader will find in Inayat Khan's hitherto unpublished lectures on the workings and hygiene of the mind and kindred subjects. This volume ends with The Mind-world, a book which was first published separately in 1935 and reprinted in 1955; its title speaks for itself. While Volume 3 contains most of Hazrat Inayat Khan's books and lectures on human relationship, Volume 4 may be considered as a continuation of Volume 2, which deals principally with the metaphysical aspect of creation, tracing a line from its origin, to the human mind.