Ancient practice
It is now well established that in the early days of Christianity it was not uncommon for infants to receive Communion immediately after they were baptized. Among others St. Cyprian (De Lapsis 25) makes reference to the practice. In the East the custom was pretty universal, and even to this day exists in some places, but in the West infant Communion was not so general. Here, moreover, it was restricted to the occasions of baptism and dangerous illness. Probably it originated in a mistaken notion of the absolute necessity of the Blessed Eucharist for salvation, founded on the words of St. John (vi, 54). In the reign of Charlemagne an edict was published by a Council of Tours (813) prohibiting the reception by young children of Communion unless they were in danger of death (Zaccaria, Bibl. Rit., II, p. 161) and Odo, Bishop of Paris, renewed this prohibition in 1175. Still the custom died hard, for we find traces of it in Hugh of St. Victor (De Sacr., I, c. 20) and Martène (De Ant. Ecc. Rit., I bk., I, c. 15) alleges that it had not altogether disappeared in his own day. The manner of Communicating infants was by dipping the finger in the consecrated chalice and then applying it to the tongue of the child. This would seem to imply that it was only the Precious Blood that was administered, but evidence is not wanting to show that the other Consecrated Species was also given in similar circumstances (cf. Sebastiano Giribaldi, Op. Mor., I, c. 72). That infants and children not yet come to the use of reason may not only validly but even fruitfully receive the Blessed Eucharist is now the universally received opinion, but it is opposed to Catholic teaching to hold that this sacrament is necessary for their salvation (Council of Trent, Sess. XXI, can. iv).
Present discipline
The existing legislation with regard to the Communion of children has been definitely settled by the Fourth Lateran Council, which was afterwards confirmed by the authority of the Council of Trent. According to its provisions children may not be admitted to the Blessed Eucharist until they have attained to years of discretion, but when this period is reached then they are bound to receive this sacrament. When may they be said to have attained the age of discretion? In the best-supported view of theologians this phrase means, not the attainment of a definite number of years, but rather the arrival at a certain stage in mental development, when children become able to discern the Eucharistic from ordinary bread, to realize in some measure the dignity and excellence of the Sacrament of the Altar, to believe in the Real Presence, and adore Christ under the sacramental veils. De Lugo (De Euch., disp. xiii, n. 36, Ben. XIV, De Syn., vii) says that if children are observed to assist at Mass with devotion and attention it is a sign that they are come to this discretion.
Thus it is seen that a keener religious sense, so to speak, is demanded for the reception of Communion than for confession. Moreover, it is agreed that children in danger of death ought to be admitted to Communion even though they may not have the same degree of fitness that would be required in ordinary circumstances. In answer to a question as to whether a certain episcopal ordinance should be upheld that fixed a definite age-limit under which children could not be admitted to First Communion, the Congregation of the Council replied in the affirmative, provided, however, that those children adjudged to have reached the discretion required by the Councils of Lateran and Trent might not be excluded (21 July, 1888). This reply bears out the interpretation already given of “the years of discretion” and it may be said in the words of the Catechism of the Council of Trent (pt. II, c. iv, q. 63) that “no one can better determine the age at which the sacred mysteries should be given to young children than their parents and confessor”.
newadvent.org/cathen/04170b.htm
