The Catholic Church is absolutely committed to a realistic and straightforward understanding of the bodily presence of Jesus in the Eucharist (see DS 1636–42/874–77, 1651–58/883–90; S.t., 3, q. 73, a. 1, ad 3; q. 75, a. 1; q. 78, a. 1). It will not do to say that the difference between the Eucharist and the other sacraments is one of degree only, on the ground that the “complete humanity of Christ, glorified body as well as soul, is active in all the sacraments.”²⁶ Jesus in glory is active—his actions are visible to us—in all the sacraments. But his own human self is bodily present in the Eucharist in a unique way (see SC 7).

Expounding the traditional teaching on the Eucharist—a tradition he says he personally received from Jesus (see 1 Cor 11.23)—St. Paul makes clear the realism of the Lord’s bodily presence in this sacrament by pointing out the implications if one receives Jesus unworthily: “Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For any one who eats and drinks without discerning the body eats and drinks judgment upon himself” (1 Cor 11.27–29). Just as unloving intercourse in marriage does not promote mutual self-giving, so the unworthy reception of Communion does not nourish the soul to eternal life. In both cases, one ought to realize what one is doing and respect the sacred reality of flesh.

The theology of “transfinalization” or “transignification” was a product of the development of understanding of the sacraments as revelatory signs and as actions. Much in this approach was excellent. However, it failed insofar as it presupposed body-self dualism and took inadequate account of the realism of Jesus’ bodily presence in the Eucharist.²⁷

One often encounters false statements such as the following: “Just as bread exists as bread only in relation to man, so what now is before him stands to him as the Body of Christ because of the new and essential relationship it has with him.”²⁸ Implicit here is a denial of the mysterious but simple truth we believe. A bodily human individual does not stand as such to others because of his or her relationship to them; on the contrary, a bodily human individual stands as such to others because he or she is this bodily person. We must recognize the body of the Lord Jesus, as Paul says. We do not create him by the projection (by faith) of Jesus-bodiliness upon a piece of bread and a cup of wine.

In the Eucharist Jesus is present bodily, not merely “by virtue of the sign and the power of the sacrament but in his proper nature and true substance” (DS 700/355). This eucharistic presence is mysterious, because this being-with-us is unique in all reality (see S.t., 3, q. 75, a. 1, ad 3; a. 4; q. 76, aa. 5–6).

However, there is nothing mysterious about the negative side of the situation (see S.t., 3, q. 75, a. 2). We know exactly what it means to point at anything which is not bread or not wine and say truly: “This is not bread; that is not wine.” In exactly the same sense that one can point at a cup of wine and say truly, “This is not bread,” or point at a piece of bread and say truly, “That is not wine,” one can point at the Bread after the consecration and say truly, “This is not bread,” and to the Cup and say truly, “That is not wine” (see DS 1256/666). For after the consecration, our Lord Jesus himself is present whole and entire, body and blood, soul and divinity, under both species (see DS 1257/667, 1639–40/876; S.t., 3, q. 76, aa. 1–2).

The whole substance—that is, the reality—of the bread is changed into the substance of Jesus’ body, and the whole substance of the wine is changed into the substance of his blood, but since he now dies no more, body and blood are not separated from each other or from his human self and divinity (see DS 1642/877, 1652/884; S.t., 3, q. 75, aa. 2, 4, 6, 8; q. 76, a. 2). It follows that we ought to worship the Eucharist, although the sacrament was instituted that we might receive Communion (see DS 1654/886, 1656/888).

Speculative theologians sometimes get into difficulties about this mystery by trying to understand it in categories other than those uniquely proper to it. But in the case of the Eucharist, just as seeing is not believing, so metaphysics is not believing. Believing is believing, and if one’s sight or reasoning leads to a different conclusion than that of simple faith, one should conclude that sight and reason are untrustworthy (see S.t., 3, q. 75, a. 1).

Less from professional theologians writing as such than in popular discussions and encounters with nonbelievers, one often receives the challenge: “If the Eucharist is understood realistically, then in receiving it you are engaging in cannibalism.” How should this challenge be answered?

There are diverse reasons why people eat human bodies. In some instances, there is a moral or religious motive for consuming a human body (or some part of it)—for example, to share in the person’s virtuous characteristics, or to keep the dead individual from reverting back into the dust from which he or she came. When such cannibalism is considered, one can see that the underlying motive is by no means repulsive; the trouble is that the method is ineffective. One does not gain courage by eating the dead heart of a noble warrior, nor preserve one’s mother from hades by digesting her dead body.

Essentially, the Eucharist is unlike cannibalism because the Eucharist does what it signifies. The sacramentality of the presence of Jesus makes available at all times and places and to all individuals for eating the one, unique, living Body who is the glorified Incarnate Word. The cannibals eat the dead remains of a person; we eat Jesus alive and glorious, and our eating neither divides nor harms him. Rather, he transforms us by, as it were, inverse digestion.