111 The Carthusians, encouraged above all by Ludolph of Saxony, found in devotion to the Sacred Heart a means of growth in affection and closeness to Christ. All who enter through the wound of his heart are inflamed with love. Saint Catherine of Siena wrote that the Lord’s sufferings are impossible for us to comprehend, but the open heart of Christ enables us to have a lively personal encounter with his boundless love. “I wished to reveal to you the secret of my heart, allowing you to see it open, so that you can understand that I have loved you so much more than I could have proved to you by the suffering that I once endured”.
Source: Dilexit Nos (Vatican.va)