The author praises Gratian’s zeal for instruction in the Faith, and speaks lowly of his own merits. Taught of God Himself, the Emperor stands in no need of human instruction; yet this his devoutness prepares the way to victory. The task appointed to the author is difficult: in the accomplishment whereof he will be guided not so much by reason and argument as by authority, especially that of the Nicene Council.

This book proposes a method of mystagogy based on the preaching of Ambrose of Milan. Chapter 1 establishes the need for mystagogy. chapter 2 lays out the historical context of Ambrose and his church. Chapters 3-8 are a series of six historical studies on Ambrose and his church that correspond to the components of a homiletic method. Chapter 9 proposes a method of mystagogy for the contemporary church based on Ambrose's preaching.

These works present the thought of Ambrose of Milan, the bishop whose preaching first renewed Augustine's interest in Christianity. Included in this volume are several of Ambrose's works on the chief points of the Christian faith: "The Mysteries," "The Holy Spirit," "The Sacrament of the Incarnation of Our Lord," and "The Sacraments," including his famous teaching on the transformation of bread and wine into the Body and Blood of Christ.