Two days after Christmas in 1673, on the Feast of St. John the Apostle, Our Lord appeared to a humble nun in an obscure convent in Paray-le-Monial, France, saying, "My Divine Heart is so inflamed with love for men, and for you in particular that, being unable any longer to contain within Itself the flames of Its burning Charity, It must needs spread them abroad by your means, and manifest Itself to them in order to enrich them with the precious graces of sanctification and salvation necessary to withdraw them from the abyss of perdition."
With these words, Our Lord entrusted to St. Margaret Mary Alacoque the mission of spreading devotion to His Sacred Heart, on fire with love for man.
On another occasion, the nun recounts:
[W]hile the Blessed Sacrament was exposed, feeling wholly withdrawn within myself by an extraordinary recollection of all my senses and powers, Jesus Christ, my sweet Master, presented Himself to me, all resplendent with glory, His Five Wounds shining like so many suns. Flames issued from every part of His Sacred Humanity, especially from His Adorable Breast, which resembled an open furnace and disclosed to me His most loving and most amiable Heart, which was the living source of these flames. It was then that He made known to me the ineffable marvels of His pure love and showed me to what an excess He had loved men, from whom He received only ingratitude and contempt.
Our Lord then said:
I feel this more than all that I suffered during My Passion. If only they would make Me some return for My Love, I should think but little of all I have done for them and would wish, were it possible, to suffer still more. But the sole return they make for all My eagerness to do them good is to reject Me and treat Me with coldness. Do you at least console Me by supplying for their ingratitude, as far as you are able.
Later, He said to her:
Behold the Heart that has so loved men that it has spared nothing, even to exhausting and consuming Itself, in order to testify to Its love; and in return, I receive from the greater part only ingratitude, by their irreverence and sacrilege, and by the coldness and contempt they have for Me in this Sacrament of Love. But what I feel most keenly is that it is hearts which are consecrated to Me that treat Me thus.
If Our Lord's words were true then, how much truer are they now, in this time of violent assaults on the sacrament of the Holy Eucharist, where heterodox bishops are pushing to allow those in the state of mortal sin to receive Holy Communion.
To make reparation for the offenses and sacrileges committed everywhere and which deeply wound the Heart of Jesus, Our Lord recommended the faithful to devote the First Friday of each month to His Sacred Heart, and made 12 promises to those who practice this devotion:
Seventy-five years after St. Margaret Mary's death, Pope Clement XIII officially approved devotion to the Sacred Heart of Jesus in 1765. The Church declared Margaret Mary Venerable in 1824, Blessed in 1864 and finally Saint in 1920. The inauguration of the Solemnity of the Sacred Heart took place in 1856.
Most Sacred Heart of Jesus, have mercy on us.