This was the favorite Marian book of St. Louis-Marie de Montfort, and inspired his “True Devotion to Mary”, which we may not have had without it, or at least not in its present form. Any book written about the “True Devotion” can ultimately trace its existence to this work. This book had a decisive and permanent influence on the Saint, and considering its influence on him, Bl. Pope John Paul II and several of his predecessors, it can be called one of the most significant books in the history of Marian spirituality and devotion. Although this book was first published in 1667, this is the first and only English translation of it.