"Behold this Heart which loves so much yet is so little loved."

What Jesus said to St Margaret Mary.

From Catholic Encyclopedia :
"On 25 May, 1671, she entered the Visitation Convent at Paray, where she was subjected to many trials to prove her vocation, and in November, 1672, pronounced her final vows. She had a delicate constitution, but was gifted with intelligence and good judgement, and in the cloister she chose for herself what was most repugnant to her nature, making her life one of inconceivable sufferings, which were often relieved or instantly cured by our Lord, Who acted as her Director, appeared to her frequently and conversed with her, confiding to her the mission to establish the devotion to His Sacred Heart. These extraordinary occurrences drew upon her the adverse criticism of the community, who treated her as a visionary, and her superior commanded her to live the common life. But her obedience, her humility, and invariable charity towards those who persecuted her, finally prevailed, and her mission, accomplished in the crucible of suffering, was recognized even by those who had shown her the most bitter opposition.

Margaret Mary was inspired by Christ to establish the Holy Hour and to pray lying prostrate with her face to the ground from eleven till midnight on the eve of the first Friday of each month, to share in the mortal sadness He endured when abandoned by His Apostles in His Agony, and to receive holy Communion on the first Friday of every month. In the first great revelation, He made known to her His ardent desire to be loved by men and His design of manifesting His Heart with all Its treasures of love and mercy, of sanctification and salvation. He appointed the Friday after the octave of the feast of Corpus Christi as the feast of the Sacred Heart; He called her "the Beloved Disciple of the Sacred Heart", and the heiress of all Its treasures. The love of the Sacred Heart was the fire which consumed her, and devotion to the Sacred Heart is the refrain of all her writings. In her last illness she refused all alleviation, repeating frequently: "What have I in heaven and what do I desire on earth, but Thee alone, O my God", and died pronouncing the Holy Name of Jesus."