From 1647-1690, Fr. John Croiset, S.J., served as spiritual director to the quiet nun to whom Our Lord Jesus Christ chose to reveal His Sacred Heart.  It was in this capacity that he composed a volume entitled The Devotion to the Sacred Heart published in 1691.  As the author neared completion of his work, Saint Margaret Mary told him that Our Lord said it was so completely in accord with His wishes that it would never be necessary to make any changes to it. Later, she revealed to Father Croiset that it was Our Lord Himself who had inspired him with the ideas in this book and that it was so pleasing to Him, that “none other but Himself could have arranged everything so much to His wishes.”

The deep and extraordinary interest taken by so many, in the devotion to the Sacred Heart of our Lord Jesus Christ, the great fruits it has produced, and the singular esteem entertained for it, by persons of universally recognized merit, have led to the publication of this book. It is intended to instruct the faithful, and satisfy their pious desires. It has been thought well to explain in the beginning, what is understood by devotion to the Sacred Heart of Jesus Christ. Experience has proved, that there is no one, who, after seeing in what it consists, does not agree, that it is reasonable, solid, and most useful, for our salvation, as well as for our perfection.