This Book Tree edition is the complete version containing all original footnotes and references. It is one of the most important books on spiritual growth ever written. This was clearly penned by a great mystic who experienced this dark night first-hand, and it describes the soul’s journey one often takes on its path toward discovering God. Many who have found God through a life-changing breakthrough have often experienced this dark night first, and this book offers one a view of what to expect and how to address such a major challenge. This version includes both Book 1 and Book 2, covering the purification of the senses and the purification of the soul, respectively. It was originally written in about 1579, when John of the Cross was jailed for trying to reform his Carmelite Order. This book remains as the most powerful guidebook of its kind up to the present day.