First we must understand what indulgences are so we don’t lapse into superstition. To do this, basic concepts must be understood, but before we get to that, let’s get a basic definition: “An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints”, (1983 Catechism ¶ 1471).

And here is what indulgences are not: they are not permission to commit sins in the future; they are not “get out of Hell free” cards; they are not the forgiveness of the guilt of sin. They have nothing to do with eternal salvation; they are only for the temporal effects of sins that have already been forgiven through Penance (or a perfect Act of Contrition, as the case may be).

OK, let’s move on to the concepts involved here:

A: Sin has two different types of effects: eternal and temporal

Sin has both eternal consequences and temporal consequences. As an example, if I were to take an innocent life, an objectively gravely sinful matter (one of the three conditions for mortal sin), under the subjective conditions of mortal sin (grave matter, full knowledge, full consent of the will), and died unrepentant, I would go to Hell. My going to Hell would be the eternal consequence of my sin.

The temporal consequences (meaning within the realm of time) of that sin range from the death of the innocent person; the suffering of my family who endured the shame and ramifications of my arrest and incarceration or enduring capital punishment; the effects of the loss of the innocent person on the family of the innocent person; the costs to the community of the loss of the innocent person; the costs to the community of litigation; the spiritual effects on the weaker members of the community whose view of the world and God’s Justice and Mercy could be affected knowing that innocent life can be taken so easily; the tarnishing of the image of the Body of Christ and the bringing of scandal upon the Church; the loss of grace in my soul and the predisposition to sin again as sin can become habitual, penance I would have to do to pay for the effects of my sin (this includes penance given to me during Confession, personal penance, and the penance assigned to me by God to be paid on earth and/or in Purgatory), etc.

If I were to repent and receive forgiveness through the Sacrament of Penance, the eternal consequences — satisfied for by Christ at Calvary — are no longer an issue (Deo gratias!) because I receive the effects of His atoning Sacrifice (I will have been justified) when I reconcile with the Church through a good Confession. But I still have to pay for the temporal consequences of my sin because God is not only merciful, He is just. An example is that of a child who steals a candy bar and then tearfully, with true contrition, confesses his crime to his parent. The parent, being loving and good and merciful, as our Father in Heaven is, will forgive that child and allow the child back in the parent’s “good graces” — but he will also, in justice, still expect the child to pay back the store from which he stole. Another example is the common one of, say, an imprisoned murderer repenting and coming to know Christ — but who still, in justice, must serve out his time in prison or give up his life as punishment.

The temporal effects of repented sins that are not paid for in life through the effects of natural law, personal penance, penance given by the priest at Confession, or mystical penances given to me by God, are paid for in Purgatory. St. Augustine, in City of God (A.D. 419), sums up Catholic thinking on such things: Temporal punishments are suffered by some in this life only, by some after death, by some both here and hereafter, but all of them before that last and strictest judgment [i.e. when Christ comes again to judge the living and the dead]. But not all who suffer temporal punishments after death will come to eternal punishments, which are to follow after that judgment.

Purgation — the process of making satisfaction for debt caused by sin so that we may become perfect, divinized, and enter Heaven — is quite Scriptural, of course. Allusions to purgation are found all over the Bible; but it is summed up most clearly in the following two verses: “Be at agreement with thy adversary betimes, whilst thou art in the way with him: lest perhaps the adversary deliver thee to the judge, and the judge deliver thee to the officer, and thou be cast into prison. Amen I say to thee, thou shalt not go out from thence till thou repay the last farthing”, Matthew 5: 25-26.

And, “Now, if any man build upon this foundation, gold, silver, precious stones, wood, hay, stubble: Every man’s work shall be manifest. For the day of the Lord shall declare it, because it shall be revealed in fire. And the fire shall try every man’s work, of what sort it is. If any man’s work abide, which he hath built thereupon, he shall receive a reward. If any mans work burn, he shall suffer loss: but he himself shall be saved, yet so as by fire”, I Corinthians 3: 12-15.

B: The temporal effects of sin affect others not only in natural, but in mystical ways

As far back as the Old Testament, it is made clear that the temporal effects of sin affect others who may not have committed personal sin. The greatest and first example is that of the sin of Adam and Eve which resulted in the fall of man from grace and in his propensity for corruption and personal sin which we call “original sin”.

The Pentateuch (i.e. Torah, the first five Books of the Bible) also speaks of the sins of the fathers being visited upon the children: “…I am the Lord thy God, mighty, jealous, visiting the iniquity of the fathers upon the children, unto the third and fourth generation of them that hate Me”, Exodus 20: 5.

I Corinthians 12: 26 demonstrates that what affects one member of the Body affects another: “And if one member suffer any thing, all the members suffer with it: or if one member glory, all the members rejoice with it”.

These concepts seem foreign to those who live in the modern Western world’s radically individualistic culture, but they are Scriptural fact. They may seem “unfair” (as though life with our fallen nature is supposed to be fair), but that it is true is obvious by looking at the often sad lives of the poor children of sexual and drug addicts or the parents of those who tend to end up in and out of juvenile detention, etc. This is not to say that those who suffer the consequences of their ancestors’ sins are doomed! No! All are called to Christ and His Church, and Jesus will judge us as individuals by looking at our hearts, wills, deeds, and intellect, taking into consideration factors which mitigate culpability. Nonetheless, the basic idea that our sins affect others not only in obvious temporal ways, but in mystical ways, is biblical.

All of these temporal punishments, though painful, are merciful. Without discipline and punishment from God, we would continue in our ways, remain unrepentant, and then suffer the eternal consequences of doing so. A father who does not discipline his children is a bad father who is setting up his child for greater troubles down the road. God, though, is a good Father: “And have you forgotten the consolation which speaketh to you, as unto children saying: My son, neglect not the discipline of the Lord: neither be thou wearied whilst thou art rebuked by Him. For whom the Lord loveth, He chastiseth: and He scourgeth every son whom he receiveth. But if you be without chastisement, whereof all are made partakers, then are you bastards, not sons. Moreover, we have had fathers of our flesh for instructors, and we reverenced them. Shall we not much more obey the Father of spirits and live? And they indeed for a few days, according to their own pleasure, instructed us: but He, for our profit, that we might receive His sanctification. Now all chastisement for the present indeed seemeth not to bring with it joy but sorrow: but afterwards it will yield to them that are exercised by it the most peaceable fruit of justice”, Hebrews 12: 5-11.

C: Grace and good works affect others in the same way

Continue reading the Exodus 20 Torah portion mentioned above: “…I am the Lord thy God, mighty, jealous, visiting the iniquity of the fathers upon the children, unto the third and fourth generation of them that hate me.  And shewing mercy unto thousands to them that love me, and keep my commandments”, Exodus 20: 5-6.

The good we do, by the grace of Christ, ripples out into creation and builds up His Body: “If so ye continue in the faith, grounded and settled, and immovable from the hope of the gospel which you have heard, which is preached in all the creation that is under heaven: whereof I Paul am made a minister. Who now rejoice in my sufferings for you and fill up those things that are wanting of the sufferings of Christ, in my flesh, for his body, which is the church…”, Colossians 1: 23-24

When we cooperate with grace — when we pray, give alms, fast, offer up our sufferings, etc. — we literally strengthen the Body of Christ in a mystical way! Christ Himself and all the Saints of 2,000 years (by the grace of Christ) have built up His Mystical Body and laid up a “treasury of merit” or “spiritual treasury,” as it is also called. In the same way we or others detract from the Body of Christ through sin, we and others add to this treasury — and receive the fruits thereof when we receive an indulgence, for we are one in the Body of Christ: “We being many, are one body in Christ, and every one members one of another”, Romans 7: 5.

And read once again I Corinthians 12: 26: “And if one member suffer any thing, all the members suffer with it:  or if one member glory, all the members rejoice with it”.

D: The Church was given the power to bind and loose

To Peter was given the Keys to the Kingdom (Matthew 16) and the power of binding and loosing (forbidding/permitting, condemning/acquitting). In exercising this power of the Keys, the Church has the authority to determine certain practices which help us to benefit from the treasury of merit and alleviate the temporal effects of sins we’ve confessed and are already forgiven for.  This is an indulgence.

That the Church was given the power to forgive the eternal effects of sin through the Sacrament of Penance makes it easier to understand how the Church also has the power to alleviate the lesser, temporal effects of sin. The Church whose priests were given the authority by Christ to forgive the guilt of sin and thereby, by the Blood of Christ, eliminate the eternal punishments for sin, surely also has the authority to pardon the temporal punishments of sin.

To refer again to the analogy of the child who steals a candy bar and repents:

The Good parent and child	Holy Mother Church and child
the parent forgives the child for stealing and allows the child back into his good graces	the Church forgives the guilt through the Sacrament of Confession, thereby eliminating the eternal consequences by the grace of Christ, and restoring the penitent from being a “dead member” of the Church to a “living member” of the Church
the child desires to pay back the store (“make satisfaction” for his debt)	the faithful desires to make satisfaction for his debt to God which he incurred through sin
the child turns to his parent for help in making satisfaction for his debt to the store. The child doesn’t have the money to pay back the store, but to the parent, the cost of the candy bar is nothing	Holy Mother Church was given the power of the Keys and, therefore, the authority to make ways for the penitent to make satisfaction for his debts to God by tapping into the treasury of merits of Christ and the Saints
the good parent says that if the child is truly contrite and truly desires to make satisfaction for the debt, he can earn enough to pay for some of the candy bar if he does X, or enough to pay for all of the candy bar if he does Y	Holy Mother Church sets out certain prayers and works to be offered under certain conditions which will either pay for some of the debt owed to God (partial indulgence) or all of the debt owed to God (plenary indulgence)
the child does X or Y	the faithful performs the prescribed actions, under the prescribed conditions, to gain an indulgence
the good parent follows through on his promise, helping the child pay for his crime by opening his wallet and giving the child some or all of the money to pay back the store.	the Church mitigates punishment incurred (temporal penalties) by opening the treasury of merit and applying those merits to the faithful

Now, suppose there are two children. One child steals the candy bar and then dies. The other child — his brother, say — wants to help pay his dead brother’s debt, so he pays back the store in the name of his dead brother.

In this way, the Catholic can offer the benefits of the indulgence to the souls in Purgatory. Indulgences can only be applied to oneself or to a soul in Purgatory, not to another living person. When applied to the souls in Purgatory, it is done only by petition to God, for those no longer of the Church Militant (the living members of the Church on earth) are not subject to the Church hierarchs who’ve been given the authority to grant indulgences.

E: Indulgences are either partial or plenary

An indulgence can be either partial, which remits only some of the temporal punishment due to sin, or plenary, which remits all temporal punishment due to sin.
 
Partial Indulgences:

Partial indulgences can be acquired as often as one desires. To gain a partial indulgence, one must do the following. These are “the usual conditions” for receiving a partial indulgence:

• be in a state of grace (free of mortal sin). A good Confession isn’t otherwise necessary, but a contrite heart for even venial sin is.
• intend to receive the indulgence
• perform the prescribed action of the indulgence

There are three General Grants of partial indulgences and many Special Grants.

The General Grants:

• First General Grant: A partial indulgence is granted to the faithful who, in the performance of their duties and in bearing the trials of life, raise their mind with humble confidence to God, adding – even if only mentally – some pious invocation.
• Second General Grant: A partial indulgence is granted to the faithful, who in a spirit of faith and mercy give of themselves or of their goods to serve their brothers in need.
• Third General Grant: A partial indulgence is granted to the faithful, who in a spirit of penance voluntarily deprive themselves of what is licit and pleasing to them.

Special Grants:

• indulgenced prayers, either recited alone, alternately with a companion, or by following it mentally as another recites it
• indulgenced works, such as the devout use of a properly blessed article of devotion (Crucifix, Rosary, scapulars, or medals), reading Scripture, making the Sign of the Cross, visits to the Blessed Sacrament, etc.

Plenary Indulgences:

Plenary Indulgences can be acquired only once each day for the same work (unless one is at the moment before death, in which case he may acquire another. Another exception is on All Souls’ Day — 2nd November — when the faithful may gain a plenary indulgence, only for the souls in Purgatory, as often as they want). Plenary indulgences are much more demanding than partial indulgences, for they require one to do the following. These are “the usual conditions” for receiving a plenary indulgence:

• Have the intention of gaining the indulgence.
• Receive the Sacrament of Penance (within several days [should not exceed 20 days] before or after the prescribed action of the indulgence, though the same day is most fittingly best, if possible).
• Receive the Eucharist (within several days before or after the prescribed action of the indulgence, though the same day is best, if possible).
• Pray 6 Paters (Our Fathers), 6 Aves (Hail Marys), and 6 Gloria Patries (Glory Bes) for the intentions of the Holy Father (within several days before or after the prescribed action of the indulgence, though the same day is best, if possible). The most recent Enchiridion (Handbook of Indulgences) prescribes at least one of each, but 6 is the traditional number.
• Perform the prescribed action of the indulgence. If the prescribed action of the indulgence requires a visit to a church or oratory, one must visit devoutly and recite 1 Our Father and the Creed. This doesn’t refer to any visits to a church for Confession or the Eucharist in order to fulfill the requirements listed above; it refers to such indulgences as those granted to the faithful for visiting a church on the day of its consecration, visiting their parochial church on its titular feast day, visiting the stational churches of Rome, etc.
• Be free from all attachment to venial sin.

This last is most difficult, but if it can’t be fulfilled, a partial indulgence will be gained.

Some examples of ways to gain a plenary indulgence:

• Adoration of the Blessed Sacrament for at least one hour.
• Making the Way of the Cross or, if unable to get to a church, the pious meditation and reading on the Passion and Death of Our Lord for a half an hour.
• Public recitation of five decades of the Rosary. This must be done vocally, continuously, and with the Mysteries announced out loud and meditated on.
• A plenary indulgence is granted on each Friday of Lent to the faithful who after Communion piously recite before an image of Christ Crucified the prayer: “Look down upon me, good and gentle Jesus…” On the other days of the year the indulgence is partial.
• A plenary indulgence is granted to the faithful who renew their baptismal promises in the liturgy of the Easter Vigil.
• A plenary indulgence is granted when an Act of Consecration is publicly recited on the Feast of the Sacred Heart of Jesus.
• A plenary indulgence is received by those who publicly make the Act of Consecration of the Human Race to the Sacred Heart on the Feast of Christ the King.
• A pious visit to a church, a public or chapel on All Souls’ Day (02 November) with the prayers of one Our Father and the Creed; this indulgence is applicable only to the Souls in Purgatory.
• A devout visit to a cemetery with a prayer, even if only mental, for the departed souls, from the first to the eighth day of November.

With any of these indulgences, one’s confessor (i.e., the priest one goes to for the Sacrament of Penance, not just any priest) may commute the work or conditions of receiving them if there is hardship.

The complete list of indulgenced prayers and works are contained in a book called the “Raccolta” or the “Enchiridion” (pronounced “en-ki-RID-ee-un” and which means “handbook” or “manual”). There are other enchiridia for other purposes, but if one speaks of “the Enchiridion” with no qualifiers, one generally means the Raccolta.

When looking at an old Enchiridion, or when reading old prayer books, one might see a period of time attached to a partial indulgence, e.g. “indulgence of 100 days”. This number indicates an amount of time of penance one was given in the early Church after a Confession, i.e., the priest would give someone a penance of a certain amount of time before he could be fully re-admitted into the Church (penances were much harsher back then!). After 1968, the indication of days in such a manner was done away with because it was not clear to some uneducated persons that the days did not refer to “time in Purgatory”. Some were under the very mistaken impression that, say, “indulgence of 100 days” meant that one would spend 100 fewer days in Purgatory instead of its true meaning: that performing the prescribed action amounts to doing a penance of 100 days.

Source: fish eaters