This book surveys the historical development of Marian belief and devotion by the Holy Spirit through the Church. How Mary was prepared and foreshadowed in the Old Testament is followed by her presence on earth as revealed in the New Testament. Then, the development of Marian doctrines and devotional practices is systematically presented. We begin by studying the early development of Marian theology in the Patristic age, which was followed by the Medieval flowering of Marian theology. Ecclesial discussions on Marian doctrine shortly before, during and after the Second Vatican Council are also presented. The subsequent three chapters focus on Marian doctrines in relationship to heresy and ecclesiology. The book ends by applying Marian belief to practice of the Catholic faith and with an appreciative gaze on Marian apparitions.