And what is the significance of the Sacred Heart? We often think of the heart as the center of the person; we speak of beating hearts, we speak of a person having a good heart, we speak of the heart when we speak of love.
It seems fitting then, that when we consider our Lord that we consider the title of the Sacred Heart. He loved us so much, that he gave himself for us. He loved us so much he allowed not only his hands to be pierced, but his heart as well. John writes of this in his Gospel:
Since it was the day of Preparation, in order to prevent the bodies from remaining on the cross on the Sabbath (for that Sabbath was a high day), the Jews asked Pilate that their legs might be broken, and that they might be taken away. So the soldiers came and broke the legs of the first, and of the other who had been crucified with him; but when they came to Jesus and saw that he was already dead, they did not break his legs. But one of the soldiers pierced his side with a spear, and at once there came out blood and water. .... (John 19:31-37)
This reminder of God's love for us, should also be a reminder of how we should love God. Jesus gave us his heart, and we should give him ours: not just when we're feeling like it, not just when things are going our way, but at times when we are joyful, and at times we feel the burden of the cross. Jesus gave himself in reparation for our sins. If we wish to imitate our Lord, then we too should try and make atonement not only the sins in our own lives (through confession, through acts of penance, fasting, sacrifices, prayer and so on), but for the sins of others. We should always remember the Church is a body of people, and that in some way we are our brother's keeper! Jesus' heart was not pierced just for me, but for all of us!
If I may paraphrase the beautiful litany to the Sacred Heart: Heart of Jesus, aflame with love for us, enthrone yourself in our hearts! Heart of Jesus, pierced with a lance, pour out love and holiness into our lives! O Sacred Heart of Jesus, you are the salvation of all who trust in you, you are the hope of all who die in you, you are the delight of all the saints!
O Sacred Heart of Jesus, have mercy on us!