On January 28th, the Church celebrates the feast of St. Thomas Aquinas. Perhaps no saintly theologian in history has been as celebrated for his Eucharistic theology: say the word “transubstantiation,” and Aquinas will likely come to mind. And yet, many in our day assume that his writings on this sacrament are too difficult or, perhaps, outdated. But as the Church in the United States seeks a Eucharistic renewal in her pastoral life, it behooves pastors and catechists to look again at the saintly doctor. They might be surprised to find that several of his works on the Eucharist are not only accessible but also timely.
Aquinas composed several studies on the Eucharist, among which the most important fall into three genres: the scholastic treatise or summa (especially the famous Summa theologiae), biblical commentary, and liturgical texts (the hymns, prayers and antiphons for the Solemnity of Corpus Christi). Now, much of the Summa requires technical training in classical philosophy, but several parts of the Summa study on the Eucharist, as well as the sixth chapter of the Commentary on John and the Office of Corpus Christi, can be read at great profit by theological novices. These texts can inform liturgical preaching and catechesis, as well as feed our spiritual lives; the biblical commentaries can aid lectio divina, while the poetic, spiritual beauty of the Corpus Christi liturgy has rarely been surpassed.
Aquinas left us many valuable insights on Eucharistic doctrine. Here, I survey two themes from his theology: the Corpus Christi liturgy’s reading of biblical figures for the Eucharist and the theology of Eucharistic communion found in the Commentary on John.
Like the Church Fathers, Thomas gave particular attention to the prophetic signs of the Christian sacraments in the Old Testament. This theme was especially dear to Aquinas, who had memorized large portions of Scripture. In the Office of Corpus Christi, the sequence sung before the Gospel reading at Mass (Lauda Sion) offers a plethora of biblical figures for the Eucharist and the Church that celebrates this sacrifice. The sequence begins with an exhortation: “Zion, Your Saviour sing, to your Shepherd and your King, sing with canticle and hymn” (translation taken from Paul Murray, OP, Aquinas at Prayer, Bloomsbury Press, 2013). The people of Israel and the holy mountain in Jerusalem are figures of Christ’s Church. The new Israel received a new sacrifice on the night of the Last Supper, a new Passover feast that Christ himself instituted: “Now the New Law’s new oblation, by the new King’s revelation, ends the form of ancient rite.”
Christ’s sacrifice on the cross fulfills all of the sacrifices of the Old Covenant, and this new offering has been given to the new people of God as a perpetual memorial. The gift of the Eucharist comes in the form of bread and wine, and for good reason: “Look! Upon the altar lies, hidden deep from human eyes, bread of angels from the skies, Made the food of mortal man.” The manna that God gave to the Israelites wandering in the desert also foreshadows the Eucharist (see John 6). It is food for the true children of God, those who follow his way, not those who imitate the rebellious Israelites in the desert: “Children’s food to dogs denied, in wondrous prophecy described: in the manna from the sky, in the binding of the boy, in the sacrificial lamb.” The Eucharist also fulfills the figure of the binding of Isaac, the only son that Abraham was willing to give up, as well as the sacrificial Passover lamb, the lamb consumed at the Last Supper.
Aquinas’ Eucharistic theology turns out to be richly biblical. Now the summit of biblical revelation on the Eucharist comes in Jesus’ bread of life discourse (John 6). Toward the end of this teaching, Christ’s interlocutors murmur in response to his perplexing instruction to eat his flesh and drink his blood. At John 6:54, Jesus responds: “He who eats my flesh and drinks my blood has eternal life.” Following St. Augustine, Aquinas explains that a share in divine life is given to those who do not merely partake of the Eucharist, but who do so worthily:
“One eats and drinks sacramentally or in a sacramental way, if he receives the sacrament; and one eats and drinks spiritually or in a spiritual way, if he attains to the reality of the sacrament. This reality of the sacrament is twofold: one is contained and signified, and this is the whole Christ, who is contained under the species of bread and wine. The other reality is signified but not contained, and this is the mystical body of Christ, which is in the predestined, the called, and the justified. Thus, in reference to Christ as contained and signified, one eats his flesh and drinks his blood in a spiritual way if he is united to him [Christ] through faith and love, so that one is transformed into him and becomes his member: for this food is not changed into the one who eats it, but it turns the one who takes it into itself, as we see in Augustine, when he says: ‘I am the food of the robust. Grow and you will eat me. Yet you will not change me into yourself, but you will be transformed into me.’ And so this is a food capable of making man divine and inebriating him with divinity. The same is true in reference to the mystical body of Christ, which is only signified (and not contained), if one shares in the unity of the Church. Therefore, one who eats in these ways has eternal life …the unity of the Church is brought about by the Holy Spirit: ‘One body, one Spirit …‘ (Ephesians 4:4).” (Thomas Aquinas, Commentary on the Gospel of John, transl. James Weisheipl and Fabian A. Larcher, Magi Press, 1980, ch. 6, paragraph 972).
This beautiful yet dense passage offers many theological insights. Those who partake of the Eucharist in faith and charity eat both sacramentally and spiritually, for this is the sacrament of charity and friendship, a sacred banquet shared by the friends of Christ. His friends receive his bodily substance, which has been signified by the consecration (“This is my body …”), and they also receive the spiritual power that flows through his sacred body, which power grants a share in God’s own life. That is, the hearts of Christ’s friends are transformed even more into a likeness of his heart, a heart burning with charity.
Thomas draws these conclusions on the foundation of Scripture, but also from his firm conviction in the bodily, substantial presence of Christ on the altar. Yet this intense focus on the mystery of transubstantiation does not lead to an individualistic spirituality, for Aquinas also insists on integrating the ecclesial mystery into his theological account. The many grains in one host and many grapes in one cup signify the unity of Christ’s members, and so, the act of partaking of this sacramental sign deepens the spiritual unity of the faithful with one another. We cannot separate our personal union with the Eucharistic Lord from our fraternal bond with our fellow Christians. Finally, Aquinas hints at his mystical understanding of the Eucharist by the language of inebriation. The Summa connects this spirituality with the bridal mysticism of the Song of Songs, chapter 5: “Eat, o friends, and drink: drink deeply, O lovers!” (Summa theologiae III, question 79, article 1, answer to objection 2).
By his Eucharistic writings, Aquinas thus invites us to deepen our understanding of this great mystery, and above all, to live it more intensely, as spouses of Christ.