Written by the spiritual director of St. Margaret Mary (1647-1690), the book comes from the pen of a man intimately familiar with every aspect of the revelations given by Our Lord to this famous Saint; thus, the book is actually the "key" to understanding the importance and centrality of the Sacred Heart devotion for our lives as Catholics. This book was actually commissioned by Our Lord through St. Margaret Mary, and as the author neared the completion of it, the Saint told him that Our Lord said it was so completely in accord with His wishes that it would never be necessary to make any change in it. This present translation is the first in English of the unabridged book and contains Fr. Croiset’s full sketch of the Saint’s life, as well as all her prayers in honor of the Sacred Heart, and a complete list of the Promises of the Sacred Heart. Paper.