At the same time the Decree «Quam Singolari» was issued, Pope Pius X appointed Cardinal Casimiro Gennari, a member of the Sacred Congregation for the Discipline of the Sacraments, to write the Commentary on the Decree itself («On the age of children’s First Communion», Brief Commentary on the Decree «Quam singulari Christus amore» by Card. Casimiro Gennari, a member of the Sacred Congregation for the Discipline of the Sacraments, Rome, At the Head Office of the Ecclesiastical Monitor, 1910). Cardinal Gennari, like nobody else, was the first to bear witness to the importance and extent of the Decree. Here are a few excerpts from this «Commentary»:

 

The Holy See, (…) has meant to dissipate the last relics of Jansenism which, under the pretext of excessive rules, turned Christians away from the Holy Table. (…) Therefore, even children must be urged to receive frequent and daily Communion, and the opposite practice is to be condemned wherever it is established. It should be noted that the recommendation concerns children only, not those who are responsible for them, namely pastors, confessors, teachers and others whom they may be entrusted to: the decree does not recommend, but obliges them (deberi), and the obligation is that they must recommend children and smooth the way for frequent and daily Communion after leading them to the Holy Table for the first time.
But that didn’t suffice to ensure the good and spiritual health of children who, in many places, or rather everywhere, made their First Communion very late, and, mostly, after ruining their innocence and after corrupting their hearts. This abuse was one of the most ruinous for children: it deprived them of the Eucharistic grace that would strengthen their soul, effectively preserving them from mortal sins, and freeing them from daily sins.
The Holy See (…) judged it necessary to issue a special general decree that gave precise and adequate rules, in order to ensure the good and health of children, especially today when many snares are laid before them in many atheist schools in order to turn them away from every sense of religion and morality. (…) Oh!  If everybody who had this duty would fulfil it faithfully! It would be the easiest and most effective way to preserve youth from the corruption that horribly spreads everywhere, and threatens to send our Catholic country back to an atrocious paganism!

Reasons for the Decree
In the first place, we must consider how Jesus loved children in his earthly life. The Gospels portray him as enchanted by their innocence, and longing to remain in their midst. (…) It was the naive soul, the pure innocence and candour of children that ravished the most loving heart of Jesus, and which brought him to propose them as a model of well-being, in order to have a greater number of places in the kingdom of heaven. (…) And if Jesus desired all of this when He was alive, shouldn’t we believe that He desires as much or that He dwells in our midst in the Most Blessed Sacrament?

First Communion to children in the early Church.
The early Church, the direct heir of the teachings and the spirit of Jesus Christ, well interpreted the Saviour’s desire to give himself in a special way to infants. And therefore, right from the beginning, it administered the Eucharist to babies immediately after Baptism. This is shown in the liturgical books of the first twelve centuries until most of the thirteenth century (Card. Bona Rer. Liturg. L. II, c.12).
It is also demonstrated in the current practice of the Greek and Oriental Churches (Benedict XIV Const. Etsi pastoralis 23 mai. 1742 no. VII). It is shown in the practice of many dioceses, during the subsequent centuries, of bringing children to the high altar immediately after Baptism (Mauleon Voyages Liturgiques, p. 27).
And since it wasn’t easy to administer Holy Communion to small children, especially nursing infants, it was the custom, since the first centuries, to administer this Sacrament to them under the species of consecrated wine only, for fear they might vomit the Eucharist. The priest dipped his finger in the chalice with the Blood, and put it in the baby’s mouth so he could suck it (Chardon Storia de’ Sacramenti L.I., Del Battes. Chap. 23). How beautiful this custom was!
And not only at Baptism did infants receive Holy Communion; but in many other occasions too. When Baptism was given on the occasion of Easter or Pentecost, the neophytes had to approach the altar for the entire octave that followed, as pointed out in a sermon given by St. Augustine (Serm. 227). In some churches it was the custom to give the Eucharist to children immediately after the clergy; however, these were placed near the sacristy (Chardon Storia dei Sacramenti, L. III Della Eucaristia, chap. 6) (…).
Therefore, the Church had no difficulty letting infants and babies take part in Holy Communion for many centuries, thus interpreting the thoughts and desires of Jesus Christ; and the Oriental Churches still practice this ancient custom. Here is another strong reason why the abuse of delaying the administration of the Most Holy Eucharist to children must come to an end.

Children’s First Communion according to the IV Lateran Council
In the thirteenth century, the practice of administering Communion to infants died out in the Latin Church. It was judged best that children receive First Communion at the first use of reason, so that this august sacrament would produce more abundant effects in their souls. (…)

Damage caused by the non-observance of this practice.
This law, which in the beginning was observed everywhere, eventually slackened. (…) But this practice became the source of serious sins, for when the child opens his mind to reason, if he has the fortune of uniting himself with Jesus in the Eucharist, begins to live His life, and continuing to approach the Holy Table finds in it the powerful antidote to free himself from daily faults and preserve himself from mortal sins, as the Council of Trent teaches. As he grows, this sacramental grace won’t fail him, and thus he will be able to preserve his innocence which is the most precious value of a Christian soul; and advance admirably on the road to virtue.
But if he delays approaching the altar; if he allows the seeds of bad habits to begin bearing evil fruits; if, having lost his innocence, he is guilty of serious sins, he finds himself on the road to ruin! He will confess his sins, it’s true; but how can he atone for the innocence he has lost? How can he uproot his evil habits? How can he restore health to the perversion of his mind and heart for which Holy Communion was an effective remedy? (…)
Famous authors testify that the number of sacrileges committed (especially when the confessors don’t assist the young penitents with prudence and charity) on the occasion of First Communions is frightful! What will be the outcome of these poor children who begin their Eucharistic life in such a bad way? We see and complain about this general corruption everywhere, which with new words is called juvenile delinquency!
And yet Jesus Christ loves children and desires to be with them! Their innocence and candour are very dear to him! Why turn them away from Him at that age in which He could pour more abundant graces into their hearts and strengthen them against temptations?
These are the serious evils that result from delaying First Communion to a more mature age. Jesus Christ is offended; the innocence of children is often bartered; they are often exposed to great sacrileges; they run the risk of perdition and ruin! (…)
These great abuses derive from the unhealthy practice of postponing First Communion! Hence the Holy See rightly condemned these abuses, reordaining the practice established by the Lateran Council and the Council of Trent which ordains Confession and Communion at the age in which children begin to reason.

Objections and responses
The reasons that usually accompany the criticism of the practice of delaying First Communion to a more mature age have no foundation.
It is said that when children approach the altar at a more mature age, they receive the Most Holy Eucharist with a greater veneration and greater fruits. But we must consider that this most divine Sacrament wasn’t instituted as a reward for virtue, but as medicine for our souls, thus the teaching of the Council of Trent (Sess. 12, c. 2) is correct when it said: «Antidotum quo liberemur a culpis quotidianis et a peccatis mortalibus praeservemur». (…)
Therefore, to approach the Holy Table, do we not want to mainly attend to the veneration due to this great Sacrament; since who could receive it worthily? But we must rather consider our need for it to strengthen our weakness and to protect us from temptations. Now who needs this life-giving food more than children who, opening their mind to the use of reason, are the weakest and most inexperienced in the battle against the enemy?
Supposing that veneration to the divine Sacrament cannot be complete in small children, it is well compensated by their innocence; in fact, innocence makes up for greater instruction: «Ignorantiam in pueris compensate innocentia» as Paludano says (ap. Gury-Ballerini T.II, no. 320, qu.5 note a). (…)
Moreover, it is said that children, before approaching the altar, must be well-educated about religious matters. The fact that all Christians are obliged to learn catechism well is beyond doubt; but that they are obliged to learn it perfectly before receiving their first Holy Communion is false. The instruction needed to receive the first sacraments consists of knowing the main mysteries of the faith and the things that concern the sacraments that are to be received. For the Eucharist it is sufficient to be able to distinguish the Eucharistic Bread from ordinary, material bread. (…)
Some people insist that if the child does not learn religious matters well before receiving his first Communion, he won’t be able to complete his instruction afterwards, given the widespread practice that after first Communion children no longer attend catechism. But this practice is a serious abuse that should be eliminated. It originates precisely from postponing first Communion to a more mature age. At this age, after the great feast of his first Communion, the child is left to his own devices without any further care: this makes his first Communion almost useless. When the young child becomes corrupted, straying from the Holy Table and from any other religious instruction, the things he once learnt soon disappear from his mind and from his heart. But if, from a young age, he approaches the altar; if he continues to receive Communion and to instruct himself; if he approaches general Communions for children with the previous preparation in the subsequent years, until he has perfectly completed his religious instruction, the above-mentioned abuse would not be deplored. He would get used to these holy exercises, and wouldn’t give them up in the following years, and his success would be assured. And this is the mind of the Sacred Congregation in the Decree we are examining, as we will see in the operative part. (…) We deny, however, that the precepts consist only of the immediate preparation for First Communion and, above all, of the innocence of life. Everyone knows that the fewer obstacles are put in the way of receiving the Most Holy Eucharist, the more fruits it will produce. Now those who receive the Eucharist at the first use of reason usually bear a pure innocence which is the most beautiful and most appropriate spirit and the dearest to Jesus Christ; unlike those who, having lived in the world, have acquired bad habits and have perhaps even committed mortal sins (V. Mon. Eccl. Vol. XXI, p. 124). (…) Therefore there is no reason that can justify the practice of postponing the first Communion of children, a practice which has become the source of great abuses.

The Holy See and the Communion of children.
The most irrational practice of postponing the First Communion of children to a more mature age and of rarely allowing them to approach the altar was always condemned by the Holy See. This is demonstrated in the first place in a letter that h.m. Pius IX made Card. Antonelli write on March 12, 1866 to the Bishops of France, for having introduced various abuses in some dioceses regarding the First Communion of children. (…) With this document, it is clear that the Holy See has always condemned the abuse of sending children away from the altar and of delaying their nourishment with heavenly bread. It wants them to approach the sacraments at a young age, so that they may receive the necessary food for spiritual life, and obtain strength and energy from it. (…)
Therefore the Holy See believed and believes that children must receive First Communion when they open their mind to the use of reason, which is the age of discretion ordained by the Lateran Council and the Council of Trent. (…)

Provisions of the Decree

I. – Age of discretion.
Notice the phrase: «begins to reason»; since it is not required that the child reasons perfectly; but, as Angelico teaches, that the child begins to have some use of reason: «quando iam pueri incipient aliqualem usum rationis habere». When therefore the mind opens itself to the first dawning of reason; and when the child can distinguish things, can recognize his parents, can express his desires, can remember the things he has done, etc.; we can say that he has reached the age of discretion.
At what age can he have such discretion? In past centuries reason was developed rather late: usually after the age of seven.
In St. Thomas’ time, a ten or eleven-year-old child could hardly begin to reason; (…) In our times this would be a paradox; since oh! how many children can now do the above things before the age of seven! Today the use of reason in little children is very precocious: everyone knows it. Little children of just three or four years old, maximum five, can reason very well, and they can distinguish normal bread from the Eucharistic Bread very well. It is said that reason is usually manifested at the age of seven. This may be true for some, but in many this takes place very earlier, and only on rare occasions after the age of seven. Therefore this is the age of discretion suitable to receive the Holy Eucharist.
However, is there an obligation to receive it at this age? The Decree clearly states it. And in fact this obligation is divine as well as ecclesiastical. «Divine», since Jesus Christ made it an obligation to receive this Eucharistic Bread (Jn. 6:54, 56): (…) However it is still «ecclesiastical» law. The precept of the IV Lateran Council is urgently needed, as we have seen before. The Decree of the Council of Trent is also urgently needed, which confirms the precept and declares anathema those who dare to deny it.
Therefore there is a serious obligation to administer the Eucharist to children as soon as they attain the use of reason.

II. – Unnecessary instruction.
The main reason of those who want to postpone the First Communion of children is that they must first learn the entire catechism, and then approach the altar. And here is our Decree to disappoint them. It declares that a full and perfect knowledge of Christian doctrine is not necessary either for First Confession or for First Communion; children only need to know the most necessary things.
And this is rightly affirmed. Since the divine and ecclesiastical precept of bringing the child before the altar when he begins to reason is urgently needed, this would be impossible if the child had to know all the Christian catechism perfectly, because it takes several years to learn it. Therefore, in order to be able to fulfil this obligation, the instruction must be limited enough for a young child. (…)

III. – Necessary instruction.
Here is what necessary instruction for first Communion consists of. The child must understand, according to his capacity, the main mysteries of faith, and be able to distinguish between the Bread of the Eucharist and ordinary bread.
The main mysteries of the faith, as everyone knows, are the mysteries of the unity and trinity of God, the incarnation, the passion and death of Our Lord Jesus Christ; and that God, as a fair judge, eternally rewards the good with heaven and eternally punishes the wicked with hell.
The child must know these mysteries as best as he can. Thus not perfectly, like theologians do, but he must be able to grasp their essence. Therefore he only needs to know that he was created by God; that this God, creator and master of everything, is one; but in Him there are three equal persons who are called Father, Son and Holy Spirit; that the second of these Persons, that is, the Son, was made man, like us, in order to save us, and for this reason suffered and died with immense pain on the cross; that those who do good deeds and observe God’s law, with the grace and merits of Jesus Christ, will be rewarded by God with heaven after death, where they will see his infinite beauty, enjoying every happiness; on the contrary, those who do evil deeds and disobey the above law and die in a state of serious sin, will be punished by God with hell, where, deprived of the sight of God, they will suffer eternal fire and every kind of evil. These are the main mysteries. (…)

IV. – Obligation and rights regarding First Communion.
We have seen before that the child has a serious obligation to go to confession and receive Communion as soon as he begins to open his mind to the use of reason. But this obligation cannot be fulfilled by the child himself without him knowing it and being assisted in fulfilling it. Therefore the Decree states that this duty belongs to those who are responsible for the child. – Who are these people? They are first of all the parents (…); secondly this duty belongs to his teachers (…); thirdly his confessors have this duty (…); fourthly it’s the pastors and priests’ duty to ensure that  all their faithful carry out the precept of Confession and Communion from the established age (…)
We have discussed the obligation of receiving this sacrament; let us now talk about the right to admit children to their First Communion. This right, according to the teachings of the Roman Catechism, belongs to the father and the confessor. The father and guardian, namely the teachers, as we have said before, and therefore the heads of boarding schools, educational institutes, schools, nursery schools and recreation centres. It is also the confessor’s duty who, after hearing the child’s confession, has the right to bring him to the altar. Does the pastor have any rights? The rights of the pastor are taken into account in the following article.

V. – General Communion of children.
As we can deduce from this article and the preceding one, First Communion can be received privately and generally. Privately when the child is brought to the altar with the help of his parents (or those who represent them) or his confessor, as the Roman Catechism rightly states. In a general manner when the children are admitted to one of the General Communions which the priest celebrates in the parish Church. If, therefore, the parents or confessor have the right to private First Communion, the parish priest has the right to general First Communion.

VI. – Frequency in receiving Communion and Catechism.
This article is of great importance. (…) After the child receives First Communion when he begins to reason, he must continue to eat this Bread of eternal life. Oh! If only he were brought to the altar daily to receive the sacred Host! How much strength, light and effective grace would enrich his soul! How, as he advanced in reason and began to know the world, he would be sound and steadfast in spirit, and he would progress admirably on the road to virtue! (…)
This regards the continuation of Communion. However, the article of the Decree also speaks about the continuation of religious instruction. After First Communion, which can be prepared for with a basic instruction, those who are responsible for the child have a serious obligation to give the child a full and perfect religious instruction, gradually, according to his ability. (…)

VII. – Confession and absolution of children.
The abuse of not confessing or not absolving children before they approached the altar, as we have already mentioned, stemmed from postponing First Communion to a more mature age.
What an intolerable abuse! All baptized believers have the right to receive the other sacraments. Why did young children have to be excluded?

IX. – Obligation of the Ordinaries concerning this Decree.
(…) The Holy Father, having considered all the facts, approved them completely; and in addition ordered the following:

a) That this Decree be promulgated and published. Therefore the contents of this Decree are not suggestions, but obligations; and not minor, but serious obligations, since this is a serious matter. The Decree was already included in the official newsletter of the acts of the Holy See; and has therefore already begun to take full effect. From this point on, all those who are responsible for children, these having attained the use of reason, have the duty to have them fulfil the double precept of Confession and Communion, and to lead them to approach frequent (and even daily if possible) Communion, along with gradual religious instruction. (…)

b) Moreover the Holy Father orders all Ordinaries to make this Decree known to the clergy and to the people. Note the Ordinaries, and Ordinaries of places, which means that this obligation belongs not only to Bishops, for their relationship with the clergy and the people of their own diocese; but also to the Superiors of religious Orders who are Ordinaries, (when they are exempt) of their own regular Clergy and of their own subjects. (…) And then we must consider that the Decree does not impose new obligations; but it refers to the fulfilment of certain and ancient obligations, which until now have been neglected. Therefore their fulfilment wouldn’t even need a formal and solemn promulgation. (…)

c) Lastly the Holy Father wants all Ordinaries to give an account of the observance of this Decree along with other diocesan matters every five years. Of course, the fulfilment of the holy and beneficial ordinances of the Decree depends mainly on the Ordinaries. Their duty is to supervise pastors, school teachers, and above all educational institutes, such as boarding schools, nursery schools, recreational centres, charitable institutions, orphanages, etc. They must give an account of the Communions which are received there and appoint zealous priests and secular religious who may assist the pastors in this very important duty, and may make the practice of children’s First Communion popular and common and encourage them to frequently approach this sacrament. Lastly it is their duty, in their holy pastoral visits, to inspect the above-mentioned educational institutes, to personally encourage children to receive holy Communion, and to possibly administer it personally in order to let children better understand its true value. These are the things which every good Ordinary will give an account of to the Holy Father, in order to bring him comfort among the great sorrow which these inauspicious times bring him. Let us make fervent vows to God that He may bless the holy diligence of Bishops, pastors and all those who are responsible for children, so that these may soon unite themselves with Jesus Christ, and continue to remain united with him in the Holy Eucharist. This is the most powerful way to save youth and to regenerate human society in a Christian way!