The heart is only the size of a fist, but its size belies its power and durability. The heart beats 4,320 times an hour, 103,680 times a day, almost 38 million times a year, and over 2.6 billion times during the course of an average life.

 It must be sturdy enough to contract and send fresh blood throughout the entire body, and elastic enough to collect spent, deoxygenated blood. Too much hardness or softness of heart, and one dies. Only a healthy heart—strong and supple—can give and receive lifeblood.

Quite simply, “heart” means “life”. To say of someone that they have “no heart” doesn’t mean simply that they lack feeling; it means that they are not life-giving.

Devotion to the Sacred Heart seems to have waned over the past few decades. It has been dismissed as bordering on magic for guaranteeing salvation for nine consecutive First Friday communions.

The exposed bleeding heart outside the body of Jesus was also felt to be both saccharine and odd at one and the same time. Yet these reservations do not account for the devotion’s striking decline, from a time when Catholic families prominently displayed a picture of the Sacred Heart in the entrance to their homes, or when holy hours and first Fridays proliferated in parishes.

Like most forms of heart distress, the decline could have been arrested by a healthy diet – of Scripture and tradition. The heart is one of the Bible’s most powerful metaphors.

It means the totality of one’s being. In the Book of Ezekiel God promises to bring about Israel’s total conversion -- He will change her “heart of stone” to a “heart of flesh.”

But it is the Gospel of John which gives the metaphor its most profound expression. According to John, the heart of Jesus is the source of living water; it provides rest for the labouring and overburdened; it strengthens the faith of the doubting Thomas; and from it flows the Church and its sacraments.

Devotion to the Sacred Heart began to flourish in the Middle Ages, because of a renewed interest in the humanity of Jesus and his passion. The seventeenth century, however, was its golden age.

The French spiritual school of Francis de Sales, Jane de Chantal, and Margaret Mary Alacoque, offered a tender, compassionate spirituality that helped to counter the severity and sectarianism of Jansenism.

It was in her Visitation Convent, from 1673 to 1675, that Margaret Mary received a series of four revelations from Jesus about his heart. It was here that devotion received its well-known form: personal consecration to the Sacred Heart, observance of an hour of prayer on Thursday night between 11 o’clock and midnight as a way of sharing in the sufferings of Jesus in Gethsemane, and the reception of communion on the first Friday of the month as reparation for the indignities inflicted upon the sacrament by the indifferent and the ungrateful.

 This latter feature would evolve into a belief that salvation was assured to those who received communion on the first Fridays of nine consecutive months.

The Sacred Heart was later enlisted as a rallying cry against the French Revolution, Communism, and threats to family life. Pius IX made it a feast of the universal Church in 1856, and Leo XIII consecrated the world to the Sacred Heart in 1899. The devotion reached its peak officially in 1956, with the theological expression in Pius XII’s encyclical, Haurietis Aquas (“You shall draw water”).

Haurietis Aquas spoke of the sacred heart as the sacrament of the passionate love of God for human beings. Qualities in the human heart of Jesus signify qualities present for us in the heart of God himself: courage, vulnerability, care, capaciousness, tenderness and compassion.

We can think of Jesus’ raising of the only son of the (doubly bereaved) widow from Naim, the restoration of son to mother, and the raising of Jairus’ daughter, ensuring that she has something to eat. Jesus’ care on these occasions is in the details.

Or we can consider how he treated the woman taken in adultery. The care lay in his silence. Or we can recall the exquisite kindness with which he healed Peter of faithlessness and betrayal.

The range of his sacred heart is broad and deep. Jesus longs to “gather” Jerusalem like a hen gathers her chicks, and desires to “draw” all to himself when lifted up. It is also close and personal, providing rest for those who labour and are overburdened, and mercy for the prodigal everyone. It is the heart of a friend, to whom we are no longer servants.

Devotions that fall into neglect need renewal, not abandonment. The late Jesuit Superior General, Pedro Arrupe, was only the latest of Church leaders to draw attention to the immense vitality of this devotion.

To him it represented a “supreme spirituality.” Having the heart of Jesus was his recommended aim to all Jesuits. But it’s not a Jesuit thing. The Sacred Heart is everyone’s hope, and everyone’s challenge. It’s the heart transplant everyone needs.