45. By the infusion of grace the heart is softened to love and strengthened for action. — Then is stone dissolved by heat, when the heart, hard and cold from the fire of divine love, is touched by that same fire of divine love, and is melted in the fervour of the Spirit, so that it burns with the ardour of desires toward the life to come, which before, hearing of it, it remained insensible. From which ardour, namely, it is both softened to love and strengthened for action, so that, as it was before hard in the love of the world, so afterward it may show itself strong in the love of God; and what before it refused to hear, it now begins both to believe and to preach.
The stone, therefore, dissolved by heat, is turned into brass, because the hard mind, liquefied by the fire of heavenly love, is changed into true fortitude, so that the sinner, who before existed insensible, may afterward become both strong through authority and resounding through preaching. Which is well said by Isaiah: 'They that trust in the Lord shall renew their strength' (Isaiah XL, 31). We change our strength, when, converted, we flee the present world with as great a virtue as we before sought it. But because a life formerly led is wickedly reckoned against us by adversaries of Catholic morals, it is rightly added: