The devotion to the Sacred Heart, like every form of Catholic worship, is derived from Christ Himself. Its origin may be found in the promise contained in John 7:38, and realised during the Passion (Jn 19:34), that “fountains of living water shall flow from His bosom”. During the Middle Ages the Sacred Heart of Jesus was identified as the source, at once physical and mystical, of this outpouring of grace. Then in the 17th century, through the experiences of a French nun, Margaret Mary Alacoque (1647-90), the Sacred Heart acquired an appeal as the expression of God’s infinite love, mercy and forgiveness to mankind. The devotion afforded a timely counter to the Jansenists, who had entertained the possibility that souls might be excluded from the saving power of grace. A notary’s daughter, and the fifth of seventh children, Margaret Alacoque was born at Lauthecourt in the diocese of Autun, Burgundy. Her family was so devout that at the age of four she made a vow of chastity, although, as she later acknowledged, she knew nothing of either vows or chastity. After a youth beset with family conflicts, Margaret entered the Visitation convent at Paray-le-Monial just before her 24th birthday. From the beginning she aroused suspicion and hostility among her fellow nuns, a cross which she bore with resignation. Then, on December 27 1673, she felt herself “invested” by the presence of Jesus, who told her that she had been chosen as the instrument and disciple of His Sacred Heart.  This conviction was enhanced over the next 18 months by further mystical experiences, through which Margaret was persuaded that she should attempt reparation for the ingratitude and hostility of mankind. A final revelation, at Corpus Christi 1675, showed her the Heart that had loved so much and been so scorned, and demanded that a feast be instituted in its honour. The nuns, not least the Mother Superior, remained unconvinced by these directions; and not until Margaret’s claims were validated by Claude de la Colombière, the rector of the Jesuit college at Paray-le-Monial, who would himself be canonised in 1992, were the more sceptical Sisters inclined to be impressed.  Even then, after Margaret informed the nuns that she had been appointed to suffer as a victim of their failings, she found that the Sisters “chose to favour me with a little sample of the grievous night of His own Passion”. In 1684 a new superior appointed Margaret assistant and mistress of the novices. Two years later the whole community at Paray-le-Monial celebrated the opening of a chapel dedicated to the Sacred Heart. Margaret was taken ill in 1690. “I shall not live,” she correctly predicted, “for I have nothing left to suffer.”