Question — Merkelbach, Summa Theologiae Moralis
Question Four: On the Subject of Confirmation
S. Th. III, q. 72, a. 6 and 8.
190. The capable subject of Confirmation is every and only a baptized man not yet confirmed (can. 786). Whence it is validly conferred upon children and the perpetually insane, who, although they have no spiritual enemies to attack, can receive spiritual strength and an increase of grace; but upon adults, provided they have at least a habitual and implicit intention of receiving the sacrament (nn. 92-93).
But that it may be received licitly and fruitfully, the one receiving it must be constituted in the state of grace, since it is a sacrament of the living, and, if he has the use of reason, sufficiently instructed (can. 786), namely both concerning those things necessary to know by necessity of means and of precept, and concerning those things which regard the sacrament to be received, as the Instruction of the S.C.P.F. of the year 1774 explains.
191. A special precept of receiving Confirmation is not given per se, because the sacrament is not necessary for salvation but for the perfection of salvation (a. 1, ad 3). Hence:
a) Those who do not receive it do not per se sin gravely.
b) But to neglect so great a means of salvation regularly, and with a sufficiently great inconvenience excluded, is not done from a reasonable motive, and therefore is accustomed to include light fault; whence can. 787: "Although this sacrament is not of the necessity of means for salvation, nevertheless it is lawful for no one, when occasion is offered, to neglect it...."
c) Per accidens grave sin can be present by reason of scandal, or contempt, or special necessity on account of a peculiar danger of losing the faith.
192. Confirmation is fitting for every age and of itself is to be given to all. - For, just as it is of the intention of nature that everyone who is born bodily arrive at perfect age, although this is sometimes impeded on account of the corruptibility of the body, which is forestalled by death, so also and much more is it of the intention of God that one who is born spiritually arrive at the perfect age of supernatural life. But the soul, to which both spiritual birth and the perfection of spiritual age pertain, is immortal, and can, just as in the time of old age it can obtain spiritual birth, so in the time of youth or childhood it can obtain perfect age, because bodily ages of this kind do not prejudice the soul. Therefore Confirmation can be conferred on every age and per se ought to be given to all (a. 8).
Hence "even in childhood man can obtain the perfection of spiritual age...; and from this it is that many in childhood, on account of the strength of the Holy Spirit received, fought strongly for Christ even unto blood" (ad 2). And this sacrament is also to be given to the dying, that they may appear perfect in the resurrection.... Whence "also children departing after having been confirmed both obtain greater glory, just as here also they obtain greater grace" (ad 4).
In the first centuries Confirmation was given immediately after Baptism. From the fifth century, on account of the multiplication of the faithful in the Latin Church, the conferral of Confirmation, as reserved to the bishop, began to be separated from the administration of Baptism; and so gradually the custom prevailed of delaying it until the years of discretion, except, however, in Spain, where the ancient custom, as among the Greeks, was preserved up to the present day.
Now the present custom of the Latin Church is more fitting, both on account of greater reverence for so great a sacrament and on account of hope of more abundant fruit in those receiving consciously. According to the present discipline consecrated by can. 788: 1. regularly Confirmation is to be delayed until the use of reason, and ordinarily is not to be administered before it; 2. nevertheless it can be conferred before this if the infant is constituted in danger of death, or if it seems to the minister expedient on account of just and grave causes; 3. yet it is not to be delayed longer, but is fittingly given at around the seventh year of age.