The first step in the transformation of the heart is overcoming all hardheartedness. Every bit of hardness, whatever its source, must be dissolved under the spell of the Sacred Heart. Our heart’s indifference toward all true values, toward the welfare of our neighbor, toward offenses against God, or the glorification of God, this indifference which is the tragedy of so many lives, this bluntness and insipidity of heart, must be dispelled under the impact of the infinite love of Christ. Hodie si vocem eius audieritis, nolite obdurare corda vestry. „Today, if you hear his voice, harden not your hearts.“
Dietrich von Hildebrand, The heart: an analysis of human an divine affectivity.