The Theology of the Spiritual Life is one the best English textbooks on spiritual theology available. The book is divided into seven parts. The first is an introduction to the study of spiritual theology in which the author defines and explains the terms 'ascetical' and 'mystical', distinguishes spiritual theology from the other branches of theology, especially moral and pastoral, explains the method and sources of spiritual theology, and adds some observations on its study. The second part treats of the nature of spiritual perfection.The next part is a brief but solid treatise on the inspirations of the Holy Spirit, the docility required by the soul to profit by these inspirations, the gifts of the Holy Ghost and their relation to perfection, and the discernment of spirits. The following section is a treatise on mental prayer, its nature, degrees, necessity, and fruit, the states and habits of mind which can help or hinder mental prayer. The sixth part is concerned with the three degrees of the spiritual life, the qualities of soul in each degree, and the differences to be considered in regard to spiritual direction. This part closes with a chapter on the active and the contemplative life. The last section is on infused contemplation, its nature and degrees, its relation to spiritual perfection, and the extraordinary phenomena which sometimes accompany infused contemplation.