II.
Backbiting drags a whole host of evils in its wake: it depraves anyone who listens to it, causes the backbiter to be considered a slanderer and incurs the hatred of his neighbor.

God has attached an enormous ball to this chain: the obligation of restoring the neighbor's reputation. Saint Augustine's words here are as true for backbiting as for money: "Non dimittitur peccatum nisi restituatur ablatum: No restoration, no pardon." (4) It is a common principle among theologians (5) that restoring their neighbor's reputation is obligatory not only for those who have revealed an imaginary crime of his, but also those who have revealed a true but secret crime. They are held to giving him at least an equivalent compensation: and they owe this compensation to the detriment not only of their own reputation, but also their life. Along with their neighbor's reputation, they must repair all the harm he has incurred; and they must do so even if what they revealed is true. Since the thing is true, they are held to tell everyone who heard them not that they were lying, but that they were backbiting.
(4) Saint Augustine, Epistle 65, Ad Macedoniae
(5) Saint Thomas Aquinas, Summa Theologica, Part II, Section II, Question 62, Article 2.

Even if it were only for the inconvenience of being obliged to repair your neighbor's reputation, backbiting should be avoided like the plague. How painful to have to retract what you said and undergo the shame of such a restoration! It is easy to return an item of clothing, a sum of money or personal property unjustly acquired; there are a thousand ways of doing it. But restoring a reputation, what a burden!

Now, the gravity of this sin lies precisely in the difficulty of repairing it. When an opinion has been revealed, it soon spreads all over, going through cities and empires, and a hitherto unknown person soon acquires a sad celebrity. But if you try and praise someone you have previously denigrated, you are wasting your time. What you said has taken root too strongly, and too many people know about it.

People believe evil first;
But when it comes to the good,
Then seeing is believing. (La Fontaine)

But you will say, "Backbiting flourishes everywhere, and no one ever makes restoration." Ah that is precisely the evil I deplore! Do you think our worst habits can excuse our vices? Just because "everyone does it", does that give you the right to do something? The vast number of fools is no praise for folly. Besides, it is false to say that reputations are never repaired. I would prefer to think it occurs only rarely. But I will admit that when there is any reparation, it is so slow, so late, so imperfect!
How rare it is for someone to return as much as he has stolen. Blind as we are, we prefer postponing everything to the supreme tribunal and awaiting the vengeance of the Lord, He who insists on justice with such severity that He prefers to remit what is due to Himself rather than what is due to others. Many people are obliged to restore after death all that they did not restore during their lifetime.
Saint Vincent Ferrer, a Spaniard, was one of the most remarkable brothers in Saint Dominic's spiritual family. He spoke so eloquently that thousands of people flocked to hear him preach and Pope Calixtus III insured that his memory would ever remain. One day Saint Vincent was preaching on the duty of repairing our neighbor's reputation. The respect due to such a great man obliges me to quote his words textually:
"The person who maliciously robs his neighbor's reputation is held to restoring it on the same level as someone who steals. If what you said is secret even though it be true, you are obliged to restore his reputation. Otherwise you will not go to heaven.
"But how can I restore it? you may ask. You must tell everyone present when you spoke ill not to believe you, that you spoke out of wickedness. If the person you defamed knows about it you are duty bound to ask his forgiveness, etc. Many have been damned for such defamations because words pass and we forget having said them; they make no scruples over them and never think of confessing them."
Thus spoke Saint Vincent, adding, "If someone neglects to do so while alive, after his death he will be obliged, despite himself, to make satisfaction to those who survive him." He confirms this teaching with the following story:
"Two men had seriously outraged their neighbor's reputation. One passed away and the other was still alive, along with the person who had been attacked. The dead man remained in the flames of purgatory for some time. After his deliverance, but before being admitted into heaven, he was commanded to completely repair the reputation of the person he had denigrated while alive. I know it is true that this soul returned to this world, for I am the man he defamed, and it is to me that he came to ask forgiveness."
O God, if a reputation is such a fragile and delicate thing, why do we not fear to contract obligations we must fulfill even after death? "Thy word, O Lord, endureth forever; it is firm as the heavens... According to Thy ordinances they still stand firm: all things serve Thee", (6) goods of both body and soul. Therefore, a good reputation is not to be scorned, for it is especially needed in fulfilling public duties. Thus it is also necessary to restore someone's reputation if we rob it in bad faith even more necessary than restoring money.
(6) Ps 118:9