1. The sacrament of the Eucharist itself

St. Thomas’s first question about the Holy Eucharist in the Summa Theologiae is Tertia Pars, Question 73, on the sacrament itself. Here, St. Thomas introduces his whole treatment of this the sacrament of sacraments, by establishing, inter alia: that the Holy Eucharist is in fact a sacrament (a. 1), that its institution was fitting (a. 5), and that it was prefigured in the old covenant (a. 6). All of these teachings of St. Thomas find their place in the Lauda Sion as well. With regard to the Holy Eucharist qualifying as a sacrament in the first place, in both verse 13 and verse 20, St. Thomas refers to the appearances of bread and wine as ‘signi/s’, with sign of course being the very genus of sacrament.Footnote ¹⁰ Verse 19 even includes the word ‘sacramento’.

In terms of this sacrament’s institution, verse 6 refers to the ‘dies … solennis …,/in qua mensae prima recolitur/huius institutio’ – that is, ‘the solemn day …, on which the first institution of this meal is recalled’. Verse 4 provides the details: ‘Quem in sacrae mensa coenae,/turbae fratrum duodenae/datum’ – ‘This was given, at the table of the holy supper, to the band of twelve brothers’. Verse 9, moreover, contains Christ’s instruction about the ritual repetition of this act: ‘Quod in cena Christus gessit,/faciendum hoc expressit/in sui memoriam’ – ‘What Christ performed at this supper, he expressed that this ought to be done in memory of him’.

Finally for this question, St. Thomas alludes to the relationship between the Holy Eucharist and its Old Testament types in verses 7 and 8 of the Lauda Sion, which generally concern the replacement of the old covenant with this the greatest sacrament of the new: ‘vetustatem novitas,/… fugat’ – ‘newness chases away oldness’. St. Thomas says. The most important locus for the foreshadowings of the Holy Eucharist, however, is verse 22: ‘In figuris praesignatur,/cum Isaac immolatur,/agnus Paschae deputatur,/datur manna patribus’ – that is, ‘In figures it is presignified, when Isaac is immolated, the paschal lamb is selected, manna is given to the fathers’. St. Thomas treats all three of these together – sacrifice, the Passover lamb, and the manna – in the Summa Theologiae as well.Footnote ¹¹ It is fitting that he should place the paschal lamb in the middle of this choral triptych in the Lauda Sion, since in the Summa he identifies this lamb as the foremost of all the Old Testament eucharistic types.Footnote ¹²

2. The species of the Eucharist

The next four questions of the Tertia Pars – and thus the next four sections of this paper – all concern the matter of the Holy Eucharist. The first of these, Question 74, focuses on the species of this matter. Again St. Thomas will include the most essential core of this question in his Lauda Sion as well. However, because this particular Summa question descends into such precise concrete details, most of what is here would be out of place in the context of liturgical praise. For example, after arguing to the most important point which is that the species of this sacrament are bread and wine (a. 1), St. Thomas treats of such minutiae as how much bread and wine there should be (a. 2), what specific sort of bread (aa. 3 & 4) and wine (a. 5) are called for, whether (a. 6) and how much (a. 8) water should be mixed in, and whether that really even matters (a. 7). All of those considerations are critical for getting the sacrament right, but they are not exactly the sorts of things one sings about.

Nevertheless, even this pragmatic question about sacramental species is echoed in the Corpus Christi sequence. St. Thomas uses the word ‘panis’ – ‘bread’ – six times in this short text, as well as ‘vinum’ – ‘wine’ – twice. In the Summa, he explains that these species are important for signifying food and drink,Footnote ¹³ since the Eucharist is precisely the sacrament of our supernatural nourishment,Footnote ¹⁴ and thus in the Lauda Sion he has the words ‘mensa’, ‘cibus’, ‘cena’, and ‘potus’ – that is, ‘meal’, ‘food’, ‘supper’, and ‘drink’ – thrice, twice, once, and once, respectively. The Summa also connects these species to the sacrifice of Christ’s Passion, with the bread and wine showing forth the separation of his body and blood,Footnote ¹⁵ which St. Thomas alludes to in verse 10 of the sequence, where he associates ‘panem, vinum’ with ‘hostiam’. Finally, even St. Thomas’s argument that the quantity of the species is unrestricted – in other words, that the priest can consecrate as much bread and wine as he wills – finds its place in the Lauda Sion, at least obliquely. Verse 16 proclaims, ‘sumit unus, sumunt mille,/quantum isti, tantum ille’ – ‘One partakes, a thousand partake, he as much as they’. In sum, much of the Summa Theologiae’s discussion of the sacramental species would translate poorly to the genre of praise, but what is most essential about these species is still included in the Corpus Christi sequence.

3. The eucharistic conversion

Question 75 is the most important question in St. Thomas’s treatment of the Holy Eucharist.Footnote ¹⁶ For it is here that St. Thomas both establishes the real presence of Christ’s body and blood in the sacrament (a. 1) and argues that such a presence is only possible if the substance of bread and wine are miraculously converted into Christ’s body and blood respectively (aa. 2–8). Both of these doctrines – the real presence and transubstantiation – are at the heart of the Lauda Sion as well.

The real, substantial presence of Christ’s body and blood is affirmed in verse 13: ‘Sub diversis speciebus,/signis tantum et non rebus/latent res eximiae’ – ‘Under diverse species, only signs and not things, hide extraordinary things’. Those ‘res eximiae’ are, of course, the body and blood of Christ – the ‘caro cibus’ and ‘sanguis potus’ of the following line – which have taken the place of the substance of bread and wine beneath those ‘signis’, beneath those ‘speciebus’. In the Summa Theologiae, St. Thomas explains that one of the great benefits of this sacramental hiding of the real presence is that it increases our faithFootnote ¹⁷ – ‘Faith is … the conviction of things unseen’ (Heb 11:1), ‘Blessed are those who have not seen and yet believe’ (Jn 20:29), etc. Likewise in verse 12 of the Lauda Sion, we sing, ‘quod non capis, quod non vides,/animosa firmat fides/praeter rerum ordinem’ – ‘what you do not understand, what you do not see, lively faith confirms beyond the order of things’. St. Thomas argues that this real presence is especially fitting for the greatest sacrament of the new covenant, since even the sacraments of the old covenant contained the figure of the sacrifice of Christ’s Passion, and it is appropriate for the reality of the new to surpass the shadow of the old.Footnote ¹⁸ Thus in verse 8: ‘umbram fugat veritas,/noctem lux eliminat’ – ‘truth chases away the shadow, light eliminates the night’.

The Corpus Christi sequence also takes up the theme of transubstantiation – that is, the radical conversion of the entire substance of bread into the entire substance of the body of Christ – and mutatis mutandis for wine and blood. Note the in-plus-accusative construction in verse 10, for example: ‘docti sacris institutis,/panem, vinum in salutis/consecramus hostiam’ – ‘Taught by these holy instructions, we consecrate bread, wine, into the victim of salvation’. That ‘into’ refers to the conversion of the one into the other, the bread or wine into the ‘salutis … hostiam’. The same in-plus-accusative construction returns in the following verse, where St. Thomas in no uncertain terms proclaims transubstantiation to be a ‘dogma’ of the Catholic faith: ‘Dogma datur Christianis,/quod in carnem transit panis/et vinum in sanguinem’ – ‘The dogma is given to Christians, that the bread passes into flesh and the wine into blood’. That ‘transit’, that ‘[passing] into’, is one of St. Thomas’s preferred verbs for the substantial conversion that takes place in the Holy Eucharist.

Nevertheless, it should be admitted that St. Thomas emphasizes transubstantiation much less in the Lauda Sion than in the Summa Theologiae – and with good reason. Whereas in the Summa more attention is given to the problem of how Christ comes to be present, the Lauda Sion focuses on the fact that Christ is present, which corresponds better to the spiritual needs of the faithful. The Corpus Christi sequence also avoids the Summa’s technical vocabulary for this conversion, which would not sing well. St. Thomas is theologically consistent across these works, and he incorporates everything essential to his eucharistic theology into the Lauda Sion. But he also knows how to adapt his theology to the liturgical, poetic genre.

4. The way in which Christ’s body is in the Eucharist

Whereas the previous question asked whether Christ is present and how he comes to be present, this Question 76 concerns how he is present, the mode in which Christ is present in the Holy Eucharist. Here, St. Thomas concludes that the whole Christ is contained under the sacrament (a. 1), that the whole Christ is contained under either species of the sacrament (a. 2), and that the whole Christ is contained under even the smallest part of either species of the sacrament (a. 3). Moreover, Christ is present in the sacrament immovably, such that nothing that happens to the eucharistic species affects or changes Christ’s body in any way (a. 6).

In verse 14 of the Lauda Sion, St. Thomas employs the very phrase ‘Christus totus’, ‘the whole Christ’, to underscore this teaching on the mode of Christ’s presence: ‘caro cibus, sanguis potus,/manet tamen Christus totus/sub utraque specie’ – ‘flesh food, blood drink, nevertheless the whole Christ remains under each species’. St. Thomas also makes a point of noting that the size of the Holy Eucharist does not matter, since Christ is as much present in the slightest sliver as he is in the largest quantity. Verse 19 reads, ‘Fracto demum sacramento,/ne vacilles, sed memento/tantum esse sub fragmento,/quantum toto tegitur’ – ‘At last, when the sacrament has been broken, do not waver, but remember that so much is under the fragment, as is covered by the whole’.

Verse 16 links this teaching on the presence of the whole Christ under the smallest bit, to the related teaching that Christ is present in this sacrament immovably: ‘sumit unus, sumunt mille,/quantum isti, tantum ille,/nec sumptus consumitur’ – ‘one partakes, a thousand partake, he as much as they, nor is the one partaken of consumed’. In other words, as much of Christ is in one host as in many, and unlike the sacramental species, Christ himself is not changed or destroyed when the Holy Eucharist is eaten. Verse 20 reiterates this latter doctrine that Christ cannot be affected in the sacrament: ‘Nulla rei fit scissura,/signi tantum fit fractura,/qua nec status nec statura/signati minuitur’ – ‘There is made no tearing of the thing, there is made only the breaking of the sign, by which neither the status nor the stature of the signified is diminished’. Verse 15 also testifies to this immoveable mode of Christ’s sacramental presence: ‘A sumente non concisus,/non confractus, non divisus,/integer accipitur’ – ‘Not cut by the partaker, not broken, not divided, he is received whole’. ‘Integer’ there, of course, harkens back to the ‘Christus totus’ of the previous verse. Christ is whole and entire, and immune to whatever changes should befall the species of bread and wine.

5. The accidents of bread and wine that remain in the Eucharist

Speaking of those species: The next question, Question 77, is on the accidents of bread and wine which persist through the transubstantiation. St. Thomas’s primary claims about this topic are that the accidents endure after the consecration without an underlying subject (a. 1), that these accidents can continue to be acted upon and to act upon other things just as they could before (aa. 3–6), and that when they do – as we have already seen in the previous section – Christ’s body and blood are not affected (a. 7).

That the accidents of bread and wine are without a subject is confirmed in verse 13 of the Lauda Sion, where St. Thomas calls the eucharistic species ‘signis tantum et non rebus’ – ‘only signs and not things’ – in other words, only accidents and not with substances underneath them as their subjects. That these accidents can continue to behave as they did before the consecration is made clear by verse 15’s participles ‘concisus’, ‘confractus’, and ‘divisus’; and by verse 16’s verb ‘consumitur’; and by verse 20’s nouns ‘scissura’ and ‘fractura’. All of these are denied of the body of Christ but affirmed of the sacramental accidents. The accidents of bread and wine can still be ‘cut’, ‘broken’, ‘divided’, ‘consumed’, and so forth, even when the bread and wine themselves are no longer present. Thus concludes St. Thomas’s treatment of the matter of this sacrament.

6. The form of the Eucharist

Question 78 of the Tertia Pars concerns the form of the sacrament. Here, St. Thomas’s most important conclusion is that the form of the sacrament proper to the bread is: ‘Hoc est corpus meum’ – ‘This is my body’; whereas the form proper to the wine is: ‘Hic est calix sanguinis mei’ – ‘This is the chalice of my blood’ (aa. 1–3). He also notices that the power of such words to effect transubstantiation means that, in addition to the omnipotence of God, there is also a created instrumental power that causes the consecration (a. 4).

Naturally the words of institution themselves do not fit into the poetic meter of the Lauda Sion, and so there is nowhere in the sequence where St. Thomas quotes the form of the sacrament directly. Nevertheless, he alludes to it in two ways: by recalling the Last Supper, where Christ first pronounced these words, and by nodding to the most important word in each of the two formulas: ‘body’ and ‘blood’. Verse 9 – already familiar to us from an earlier section – is the relevant allusion to the institution of the form: ‘Quod in cena Christus gessit,/faciendum hoc expressit/in sui memoriam’ – ‘What Christ performed at this supper, he expressed that this ought to be done in memory of him’. Of course, Christ’s ‘Do this in memory of me’ comes immediately after the form of the sacrament in both St. Luke’s and St. Paul’s accounts. The thing to be ‘done in memory of him’ is precisely the pronouncing of these words. In terms of the words themselves, it should be noted that St. Thomas exchanges the ‘corpus’ of the words of institution for the ‘caro’ of the Bread of Life Discourse, the Johannine text that St. Thomas also selects for the alleluia verse sung immediately before this sequence and for the Gospel proclaimed immediately after. Granting that substitution, one finds that St. Thomas gestures to the form of the sacrament by using the words ‘flesh’ and ‘blood’ – ‘caro’ and ‘sanguis’ – twice each, in verses 11 and 14. Finally, St. Thomas’s insistence in the Summa that there is a created instrumental power effecting the consecration with God is confirmed here in the word ‘consecramus’ from verse 10: Not God alone, but ‘we consecrate’, and that precisely through the form of the sacrament.Footnote ¹⁹

7. The effects of the Eucharist

Having treated both the matter and the form of the sacrament, St. Thomas proceeds in Question 79 to consider its effects. For those who benefit from it, he says, the Holy Eucharist: bestows grace (a. 1), causes the attainment of glory (a. 2), forgives past venial sins (a. 4), and prevents future sins (a. 6). St. Thomas also uses this question to clarify that the Holy Eucharist is both sacrament and sacrifice, both something received and something offered (a. 5).

The Corpus Christi sequence likewise teaches that the Holy Eucharist gives grace, when it refers to this sacrament as ‘panis vivus et vitalis’ in verse 3: ‘living and life-giving bread’. The life in question, of course, is the supernatural life of the soul, made possible by sanctifying grace. Verse 23 makes reference both to the forgiving of past sins – ‘Iesu nostri miserere’ – and to the preventing of future sins – ‘tu nos pasce, nos tuere’: ‘Jesus, have mercy on us, feed us, protect us’. This same verse refers to the Holy Eucharist as cause of future glory as well: ‘tu nos bona fac videre/in terra viventium’ – ‘make us to see good things in the land of the living’. The next and final verse of the sequence, verse 24, is all about glory: ‘Tu qui cuncta scis et vales,/qui nos pascis hic mortales,/tu nos ibi commensales,/coheredes et sodales/fac sanctorum civium’ – ‘You who know and can do all things, who feed us mortals here, there make us table companions, coheirs, and comrades of the holy citizens’.

In terms of the Holy Eucharist as sacrifice, recall that St. Thomas identifies Isaac and the paschal lamb as its prefigurations in verse 22. As for the Eucharist as sacrament, we have already seen that the very word ‘sacramento’ appears in verse 19. But even beyond this, since St. Thomas distinguishes the Eucharist as sacrament precisely according to its being received rather than offered,Footnote ²⁰ it is noteworthy that the Lauda Sion uses variations on the word ‘sumere’ or ‘receive’ seven times in just four verses, namely verses 15–18 (eight times if you count ‘consumitur’).

8. The use of the Eucharist

Whereas the other sacraments are completed only in the use of their matter, the Holy Eucharist is completed in the very consecration of its matter.Footnote ²¹ Nevertheless, St. Thomas says in the Summa, ‘Finis autem huius sacramenti est usus fidelium’ – ‘The end of this sacrament is the use of the faithful’.Footnote ²² And so St. Thomas devotes Tertia Pars, Questions 80 and 81, to the use of the Holy Eucharist. Question 80 is about its use in general, and Question 81 about the use that Christ made of it at the Last Supper – for example, whether he consumed the Eucharist himself (a. 1), and whether he gave the sacrament to Judas (a. 2). However, because a liturgical sequence is not the place to argue about such contentious issues of exegesis, we will keep our focus here on Question 80, on the use of the sacrament in general. The most essential doctrines from this question are that the sacrament itself is the same regardless of who receives it (a. 3), but that this selfsame sacrament has very different effects on the just who eat it spiritually, as on the unjust who eat it merely sacramentally (a. 1) – and this because the unjust sin gravely by receiving it without first repenting of their sins (a. 4). St. Thomas also uses this question to reflect on the relationship between the Holy Eucharist and the holy angels, whom he says spiritually feed on the one contained in the Eucharist, but not precisely under the eucharistic species (a. 2).

The two stanzas of the Lauda Sion that speak most directly to the question of saving versus sinful eating are verses 17 and 18: ‘Sumunt boni, sumunt mali,/sorte tamen inaequali,/vitae vel interitus; // mors est malis, vita bonis;/vide, paris sumptionis/quam sit dispar exitus’ – ‘Good men partake, evil men partake, nevertheless with an unequal lot, of life or of destruction; death is for the evil, life for the good; behold, of equal partaking how unequal is the consequence’. The contrast could not be more clear.

In the context of the Summa Theologiae, one might have been forgiven for thinking that Question 80, Article 2 – on the angels and the Eucharist – was a bit tangential, and ultimately not so important for understanding the Blessed Sacrament. However, the most famous line of the Lauda Sion corresponds to this very article. Verse 21 proclaims, ‘Ecce, panis angelorum,/factus cibus viatorum,/vere panis filiorum,/non mittendus canibus’ – ‘Behold, the bread of angels, made the food of wayfarers, truly the bread of sons, not to be given to the dogs’. This latter couplet, referencing Christ’s words to the Syrophoenician woman in Mark’s Gospel, serves as yet another caution against the merely sacramental eating by the unjust. But the former couplet – ‘Ecce, panis angelorum,/factus cibus viatorum’ – draws the connection between this sacrament and the angels, identifying the Holy Eucharist that we consume as properly ‘the bread of angels’. Why is this? After all, the angels do not have bodies, and so they can neither sense nor eat the sacrament. Nevertheless, St. Thomas explains in the Tertia Pars, ‘The angels spiritually eat Christ himself, inasmuch as they are united to him by the enjoyment of perfect charity and by manifest vision – which is the bread we await in the fatherland’.Footnote ²³ The Holy Eucharist is ‘the bread of angels’, therefore, because they enjoy the one contained therein more perfectly and delightfully than we do as pilgrims here below. Moreover, St. Thomas says, because

‘Ecce panis angelorum’ indeed.

9. The minister of the Eucharist

In Question 82, St. Thomas treats the minister of this sacrament, namely the priest. Only a priest can consecrate the Holy Eucharist, St. Thomas teaches, because only the priest has been ordained to act in the very person of Christ for performing this sacrament (a. 1). The Lauda Sion makes reference to these priestly ministers first by recalling that Christ originally gave this sacrament only to the ‘turbae fratrum duodenae’ – i.e., the first Christian priests the apostles – in verse 4, to whom also Christ gave the instruction to repeat it in his memory, in verse 9. Verse 10’s first-person plural ‘consecramus’ is also telling in this regard: At this point in the sequence, St. Thomas is speaking specifically to his brother priests and on behalf of all of them, who ‘consecrate’ the Holy Eucharist, with ‘Christianis’ in general placed in the third person in the following verse, and then the individual Christian becoming the direct addressee of the verse after that. It is fitting that this Corpus Christi sequence should open up in this way, like Adam of St. Victor’s Laudes Crucis Attollamus upon which it is based,Footnote ²⁵ but also like the Holy Eucharist itself, which passes from Christ to the priest as mediator, and through him to the people.

10. The rite of the Eucharist

The final question in St. Thomas’s Tertia Pars consideration of the Holy Eucharist is Question 83, on the rite of this sacrament. This is one of the most involved questions in all of the Summa Theologiae – no article in the Summa has more objections than Article 5 here, for example, about the particular gestures of the eucharistic liturgy. Of course, the Corpus Christi sequence does not rehearse all of the specifics of the liturgy of the Mass, but nevertheless it does make reference to this ritual. For example, verse 10’s ‘docti sacris institutis’ refers to everything that Christ himself absolutely required for the rite of the Mass. Verse 16’s ‘sumit unus, sumunt mille’ alludes to the rite for the reception of Holy Communion, by the priest celebrant and then by the faithful. And most concretely, verse 19’s ‘Fracto demum sacramento’ refers to the fraction rite, when the priest breaks the host in order to put a small piece of it – the fraction – into the chalice.

11. Conclusion

All of the essential doctrines of St. Thomas Aquinas’s eucharistic theology find a home in his sequence for the Mass of Corpus Christi, the Lauda Sion. These doctrines are elevated, moreover, from their usual genre of speculative theology, into the highest of all genres: the laudatory. Naturally a liturgical sequence is always a matter of praise, by necessity, just given its placement alongside the alleluia in the eucharistic liturgy. But to drive home the point that praise is particularly the point of this sequence, St. Thomas uses variations on the word ‘laus’ six times in just the first five verses, including of course as the very first word of the text and so also of its title: ‘Lauda, Sion, salvatorem’ – and in case that was not sufficiently clear, the second line starts just the same way: ‘lauda ducem et pastorem’. The Holy Eucharist is a ‘laudis thema specialis’, in verse 3: a ‘theme of special praise’. Verse 5 asks that this ‘laus’ be ‘plena’ and ‘sonora’: that this ‘praise’ be ‘full’ and ‘resounding’. But perhaps it is verse 2 that says it most perfectly: Even when every eucharistic doctrine has been brought up and turned to the praise of Christ in the Holy Eucharist, still it is not enough, because the one contained in this sacrament is infinitely greater than anything we could ever offer him, even when we offer the perfect doxological compendium of St. Thomas’s eucharistic theology that is the Lauda Sion: ‘Quantum potes, tantum aude,/quia maior omni laude,/nec laudare sufficis’ – ‘As much as you can, be that bold,/because he is greater than every praise,/nor do you suffice to praise him’.