First published in 1938, this book made a significant contribution to the scholarship on mysticism by approaching the problems of mysticism from the theological angle adopted by the church fathers and medieval scholastics. Seeking to strike a balance with the psychological method, Stolz began his study with an examination not of John of the Cross or Teresa de Avila, but of St. Paul's account of his rapture. Stolz's analysis clarified the theological foundation of mysticism and its development in the ecclesiastical tradition, with his assertion that "mysticism is built on the sacramental and therefore the liturgical life, and is thus bound up intrinsically with Christian life, of which it is the conscious intensification and perfection."