In the 1925 Pontevedra Marian Apparition, Jesus appeared alongside the Blessed Virgin Mary, and while resting his hand on her shoulder, expressed His desire: “I want my heart to be honored side by side with the heart of My Mother.”
This devotion to the Alliance of the Two Hearts was later reinforced in another revelation. When Sister Lucia asked Our Lord why He would not convert Russia without its consecration to the Immaculate Heart of Mary, Our Lord replied :
“Because I want My whole Church to acknowledge that Consecration as a triumph of the Immaculate Heart of Mary, so that it may extend its cult later on, and put the Devotion to My Mother’s Immaculate Heart beside the Devotion to My Sacred Heart.”
In the 1830 Marian apparition, Our Lady showed St. Catherine Labouré the design of a medal, which would obtain abundant graces for those who wore it faithfully, especially the grace of conversion for sinners.
On the reverse side of this Miraculous Medal, one finds a theological symbol: the Cross of Christ surmounted by the letter “M,” and underneath, the Sacred Heart of Jesus and the Immaculate Heart of Mary positioned side by side.
This divinely requested design serves as a powerful affirmation of the inseparable bond and devotion to her holy heart.
Unlike the Heart of Jesus, the Heart of Mary does not participate in the hypostatic union. It is the heart of the most perfect of creatures who took the love of God to the highest point possible and was closely united to the Heart of Jesus in a maternal and filial intimacy.
“In order that favors in greater abundance may flow on all Christians, nay, on the whole human race, from the devotion to the most Sacred Heart of Jesus, let the faithful see to it that to this devotion the Immaculate Heart of the Mother of God is closely joined.” (Pope Pius XII, Encyclical Haurietis Aquas (1956)
Following the apparitions of Our Lady of Fatima, the Feast of the Immaculate Heart of Mary was instituted for the universal Church by Pope Pius XII in 1944. Originally celebrated on August 22nd, the octave day of the Solemnity of the Assumption, the feast was later moved to the Saturday immediately following the Solemnity of the Sacred Heart. This change ensures that the Two Hearts appear side by side, on Friday and Saturday, on the liturgical calendar.
Together, the two devotions call for the faithful to offer reparative prayers and Sacraments to both the Sacred Heart of Jesus and the Immaculate Heart of Mary.