In the XVII century Saint Margaret Mary Alacoque, Visitation nun, had several visions of Jesus Christ showing her his Heart and telling her: Behold the Heart which has so loved men that it has spared nothing, even to exhausting and consuming Itself, in order to testify 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. Thanks to these visions, and mostly thanks to the "12 promises" made by Jesus Himself, the devotion to the Sacred Heart of Our Lord spread all over the world, in particular with the practice of the First Nine Fridays and the institution of the liturgical solemnity. There is a connection between the Holy Rosary and Jesus' heart too. In fact, by meditating on Christ's life we can think about his Heart: a human one, a true one beating for each one of us on this earth, and feeling joy, pain, sorrow, and above all love, the greatest love that led Jesus to die for the humankind. And this human and divine Heart is still burning with love for every human creature: it is the Heart of Our Risen Saviour. Several Popes, especially in recent times, spoke in many occasions about Jesus' Heart, and the brief meditations accompanying each mistery of this Holy Rosary are taken from their Magisterium. So we will be introduced by saint Peter's successors into the wonderful and eternal mistery of the living Heart of Jesus Christ.