Habits acquired by our human actions alone do not perish by one single contrary act: for a man is not said to be intemperate for one single act of intemperance, nor is a painter held an unskilful master for having once failed in his art; but, as all such habits are acquired by the influence of a series of acts, so we lose them by a long cessation from their acts or by many contrary acts. But charity, Theotimus, which in a moment the Holy Ghost pours into our hearts as soon as the conditions requisite for this infusion are found in us, is also in an instant taken from us, as soon as, diverting our will from the obedience we owe to God, we complete our consent to the rebellion and disloyalty to which temptation excites us.
It is true that charity increases by degrees and goes from perfection to perfection according as by our works or by the frequenting of the sacraments we make place for it, yet it does not decrease by a lessening of its perfection, for we never lose any least part of it but we lose it all. In which it resembles the masterpiece of Phidias so famous amongst the ancients; for they say that this great sculptor made at Athens an ivory statue of Minerva, twenty-six cubits high, and in the buckler which she held, wherein he had represented the battles of the Amazons and Giants, he carved his own face with so great art that one could not take away one line of it, says Aristotle, without destroying the whole statue, so that this work, though it had been brought to perfection by adding piece to piece, yet would have perished in an instant if one little parcel of the workman's likeness had been removed. In like manner, Theotimus, though the Holy Ghost having infused charity into a soul increases it by adding one degree to another and one perfection of love to another, yet still, the resolution of preferring God's will before all things being the essential point of sacred love, and that wherein the image of eternal love, that is of the Holy Ghost, is represented, one cannot withdraw one single piece of it but presently charity wholly perishes.
This preference of God before all things is the dear child of charity. And if Agar, who was but an Egyptian, seeing her son in danger of death had not the heart to stay by him, but would have left him, saying: Ah! I will not see the child die,  is it strange then that charity, the daughter of heavenly sweetness and delight, cannot bear to behold the death of her child, which is the resolution never to offend God? So that while free-will is resolving to consent to sin and is thereby putting to death this holy resolution, charity dies with it, saying in its last sigh: Ah! no, never will I see this child die. In fine, Theotimus, as the precious stone called prassius loses its lustre in the presence of any poison, so in an instant the soul loses her splendour, grace and beauty, which consist in holy love, upon the entry and presence of any mortal sin; -- whence it is written that the soul that sinneth, the same shall die. 
 Genesis 21:16.  Ezech. xviii. 4.
 Ezech. xviii. 4.