Father John Croiset of the Society of Jesus wrote this book in the earliest days of the devotion to the Sacred Heart, and it has never been bettered as a plain explanation of what that devotion is and how a soul actually practices it. This edition follows the English translation published in London in 1863 with the imprimatur of Cardinal Wiseman. Father Croiset begins by clearing away the confusion, since he knew that the very title would draw some readers and put others off, and he sets out simply what devotion to the Sacred Heart consists in: the love Jesus Christ has for us, the reparation owed for the contempt that love receives, and an ardent love for the person of Christ as the fruit. He then gives the motives, the excellence of the Heart of Jesus, the sensible proofs of His love for us, and the ingratitude of men in return. The second part is the most practical thing in the book. Father Croiset names the dispositions a soul needs, a horror of sin, a lively faith, a real desire to love Christ, and interior recollection, and then names the four things that block the fruit of this devotion: tepidity, self-love, a secret pride, and some unmortified passion. Against them he sets true mortification, sincere humility, prayer, frequent Communion, and visits to the Blessed Sacrament.
 
The third part is the devotion itself, laid out so a man can begin it tomorrow. There is the practice for the feast day, for the first Friday of each month, for every week, and for every day, along with the Act of Reparation, the Act of Consecration to the Sacred Heart, acts of love, adoration and contrition, an offering to be made during Mass, and the prayer St. Gertrude recited daily in honor of the Sacred Heart. The book closes with meditations for the feast and for each first Friday. Father Croiset also gives the account in Father de la Colombière's own words, taken from the journal of his retreat in London, of Our Lord disclosing His Heart and asking that the Friday after the Octave of the Blessed Sacrament be kept in reparation. Glorious Heritage Books has reset this edition in clean, readable type, with the 1863 translation kept as it was written. This is one of the books that carried the Sacred Heart into Catholic homes in the first place, and it deserves to be back on the shelf.