"Behold the Heart which has so loved men that it has spared nothing, even to exhausting and consuming Itself, in order to testify Its love; and in return, I receive from the greater part of souls only ingratitude..." 

“It was to Margaret Mary Alacoque (1647-1690), a humble Visitandine of the monastery at Paray-le Monial, that Christ chose to reveal the desires of His Heart and to confide the task of imparting new life to the devotion. There is nothing to indicate that this pious religious had known the devotion prior to the revelations, or at least that she had paid any attention to it. These revelations were numerous, and the following apparitions are especially remarkable:

• That which occurred on the feast of St. John, when Jesus permitted Margaret Mary, as He had formerly allowed St. Gertrude, to rest her head upon His Heart, and then disclosed to her the wonders of His love, telling her that He desired to make them known to all mankind and to diffuse the treasures of His goodness, and that He had chosen her for this work (27 Dec., probably 1673)

• When He appeared radiant with love and asked for a devotion of expiatory love … frequent Communion, Communion on the First Friday of the month, and the observance of the Holy Hour (probably June or July, 1674)

• The “great apparition” which took place during the octave of Corpus Christi, 1675, probably on 16 June, when He said, “Behold the Heart that has so loved men … instead of gratitude I receive from the greater part (of mankind) only ingratitude …”, and asked her for a feast of reparation of the Friday after the octave of Corpus Christi

• And finally, those in which solemn homage was asked on the part of the king, and the mission of propagating the new devotion was especially confided to the religious of the Visitation and the priests of the Society of Jesus

A few days after the “great apparition”, of June, 1675, Margaret Mary made all known to Father de la Colombiere, and the latter, recognizing the action of the spirit of God, consecrated himself to the Sacred Heart, directed the holy Visitandine to write an account of the apparition, and made use of every available opportunity discreetly to circulate this account through France and England. At his death, 15 February 1682, there was found in his journal of spiritual retreats a copy in his own handwriting of the account that he had requested of Margaret Mary, together with a few reflections on the usefulness of the devotion. 

This journal, including the account and a beautiful “offering” to the Sacred Heart, in which devotion was well explained, was published at Lyons in 1684. The little book was widely read, even at Paray, although not without being the cause of “dreadful confusion” to Margaret Mary, who, nevertheless, resolved to make the best of it and profited by the book for the spreading of her cherished devotion. Outside of the Visitandines, priests, religious, and laymen espoused the cause, particularly a Capuchin, Margaret Mary’s two brothers, and some Jesuits, among the latter being Fathers Croiset and Gallifet, who were destined to do so much for the devotion.”(Excerpt from the Catholic Encyclopedia, 1917)