This book is a compendium of works by St. Ignatius Loyola and other early Jesuits. The works are meant to be a resource for Jesuits in their spiritual lives. It contains such items as the Spiritual Exercises of St. Ignatius, along with a Directory (or manual) on how to use these exercises. It also has various rules or guidelines for Jesuits who have specific roles or duties in the order. There are two Latin versions of the Spiritual Exercises printed in this book. One is the so-called "versio vulgata" and the other is the "versio litteralis." There are accompanying notes for these versions by Fr. Jan Roothaan written about 1920.