Section — Wouters, Manual of Moral Theology
Section I. On the Notion and Division of Reception of the Holy Eucharist
The reception of the Eucharist can be distinguished as threefold, namely material, sacramental, and spiritual.1
I. Material reception is that by which it is so received that the sacrament is not applied to the one receiving, in other words, so that the sacrament does not become a title of grace applied to him. It is received materially: 1. by one not baptized; 2. by a baptized adult who lacks intention.
II. Sacramental reception is had when the sacrament is applied to the one receiving, or when it becomes a title of grace applied to the one receiving. Sacramental reception is twofold, namely sacramental only, and sacramental and spiritual, according as it is received with or without an obstacle to the effect, that is, to the grace to be received.
As regards the requisites for sacramental reception, receive these points:
For sacramental reception, eating is certainly required, whether true or equivalent. This is drawn from these words of Christ: "Unless you eat the flesh of the Son of man and drink His blood, you will not have life in you";2 "Take and eat; this is my body";3 "... drink ye all of this, for this is my blood of the New Testament, which shall be shed for many unto remission of sins."4
For sacramental reception, the passage of food into the stomach is certainly required. For if this is lacking, according to common estimation no one is said to eat.
It is disputed whether or not a vital passage into the stomach through the esophagus, whether natural or artificial, is required, or whether passage into the stomach by means of a tube inserted into the esophagus or into another part of the body suffices. Some judge that passage by means of a tube suffices, because there is at least equivalent eating. Others admit the contrary, because, considering the obvious sense of the words of Christ, there seems to be required an act which truly is, or at least according to common estimation is called, eating. Now one who is fed by means of a tube is not said to eat, but to be nourished artificially.
III. Spiritual reception is the desire or vow, conceived from faith and charity, of receiving the Eucharist really.5 Now spiritual Communion produces ex opere operantis fruits very similar to those which real Communion effects ex opere operato. Hence the Council of Trent declares that those communicate spiritually "who, eating in desire that heavenly bread set before them, by living faith which works through love, perceive its fruit and usefulness."6 But in order that someone may acquire the aforesaid fruits, let him elicit an act of faith, charity or perfect contrition, and desire toward Christ in the Eucharist. One who is only attrite concerning a mortal sin perhaps committed, by desiring Communion indeed performs a good work, but does not communicate spiritually, and therefore does not receive the special fruits annexed to spiritual Communion.
In the following, the discussion will be only about sacramental Communion.
1 "As regards use, the Council of Trent speaks thus: 'Our fathers rightly and wisely distinguished three ways of receiving this holy sacrament. For they taught that some receive it sacramentally only, as sinners; others only spiritually, namely those who, eating in desire that heavenly bread set before them, by living faith which works through love, perceive its fruit and usefulness; and thirdly, others both sacramentally and spiritually; and these are those who first so prove and prepare themselves that, clothed in the wedding garment, they approach this divine table'" (Session 13, chapter 8).
2 John 6:54.
5 Council of Trent, session 13, chapter 8.
6 Loc. cit.