First, the image of the blood shed on the Cross, and the water and blood from the Piercing of Christ's Body recalls the great gift of mercy, Redemption, and the Holy Eucharist.
Second, the reference to reparation reminds one that by keeping this feast, Christ joins in our own suffering, as Man and as God.
Third, we make reparation by honoring the Sacred Heart today. Again, I share my favorite painting, the original rendition of the Sacred Heart by Batoni, found in the Gesu, with a copy in the Church of the Circumcision in Malta.
From the writing of St. Margaret Mary Alacoque:
“The Divine Heart was presented to me in a throne of flames, more resplendent than a sun, transparent as crystal, with this adorable wound. And it was surrounded with a crown of thorns, signifying the punctures made in it by our sins, and a cross above signifying that from the first instant of His Incarnation, […] the cross was implanted into it […].” more found here on the painter, painting and devotion...http://www.divinarivelazione.org/index.php?option=com_content&view=article&id=717&Itemid=1016&lang=en