Summa Th. III EN Qu.73 a.6
Objection: 1. It seems that the Paschal Lamb was not the chief figure of this sacrament, because (Ps 109,4) Christ is called "a priest according to the order of Melchisedech," since Melchisedech bore the figure of Christ's sacrifice, in offering bread and wine. But the expression of likeness causes one thing to be named from another. Therefore, it seems that Melchisedech's offering was the "principal" figure of this sacrament.
2. Further, the passage of the Red Sea was a figure of Baptism, according to 1Co 10,2: "All . . . were baptized in the cloud and in the sea." But the immolation of the Paschal Lamb was previous to the passage of the Red Sea, and the Manna came after it, just as the Eucharist follows Baptism. Therefore the Manna is a more expressive figure of this sacrament than the Paschal Lamb.
3. Further, the principal power of this sacrament is that it brings us into the kingdom of heaven, being a kind of "viaticum." But this was chiefly prefigured in the sacrament of expiation when the "high-priest entered once a year into the Holy of Holies with blood," as the Apostle proves in He 9. Consequently, it seems that that sacrifice was a more significant figure of this sacrament than was the Paschal Lamb.
On the contrary The Apostle says (1Co 5,7-8): "Christ our Pasch is sacrificed; therefore let us feast . . . with the unleavened bread of sincerity and truth."
I answer that We can consider three things in this sacrament: namely, that which is sacrament only, and this is the bread and wine; that which is both reality and sacrament, to wit, Christ's true body; and lastly that which is reality only, namely, the effect of this sacrament. Consequently, in relation to what is sacrament only, the chief figure of this sacrament was the oblation of Melchisedech, who offered up bread and wine. In relation to Christ crucified, Who is contained in this sacrament, its figures were all the sacrifices of the Old Testament, especially the sacrifice of expiation, which was the most solemn of all. While with regard to its effect, the chief figure was the Manna, "having in it the sweetness of every taste" (Sg 16,20), just as the grace of this sacrament refreshes the soul in all respects.The Paschal Lamb foreshadowed this sacrament in these three ways. First of all, because it was eaten with unleavened loaves, according to Ex 12,8: "They shall eat flesh . . . and unleavened bread." As to the second because it was immolated by the entire multitude of the children of Israel on the fourteenth day of the moon; and this was a figure of the Passion of Christ, Who is called the Lamb on account of His innocence. As to the effect, because by the blood of the Paschal Lamb the children of Israel were preserved from the destroying Angel, and brought from the Egyptian captivity; and in this respect the Paschal Lamb is the chief figure of this sacrament, because it represents it in every respect.
Reply to Objection: 1. From this the answer to the Objections is manifest.
We have now to consider the matter of this sacrament: and first of all as to its species; secondly, the change of the bread and wine into the body of Christ; thirdly, the manner in which Christ's body exists in this sacrament; fourthly, the accidents of bread and wine which continue in this sacrament.
Under the first heading there are eight points for inquiry:
(1) Whether bread and wine are the matter of this sacrament?
(2) Whether a determinate quantity of the same is required for the matter of this sacrament?
(3) Whether the matter of this sacrament is wheaten bread?
(4) Whether it is unleavened or fermented bread?
(5) Whether the matter of this sacrament is wine from the grape?
(6) Whether water should be mixed with it?
(7) Whether water is of necessity for this sacrament?
(8) Of the quantity of the water added.
Objection: 1. It seems that the matter of this sacrament is not bread and wine. Because this sacrament ought to represent Christ's Passion more fully than did the sacraments of the Old Law. But the flesh of animals, which was the matter of the sacraments under the Old Law, shows forth Christ's Passion more fully than bread and wine. Therefore the matter of this sacrament ought rather to be the flesh of animals than bread and wine.
2. Further, this sacrament is to be celebrated in every place. But in many lands bread is not to be found, and in many places wine is not to be found. Therefore bread and wine are not a suitable matter for this sacrament.
3. Further, this sacrament is for both hale and weak. But to some weak persons wine is hurtful. Therefore it seems that wine ought not to be the matter of this sacrament.
On the contrary Pope Alexander I says (Ep ad omnes orth. i): "In oblations of the sacraments only bread and wine mixed with water are to be offered."
I answer that Some have fallen into various errors about the matter of this sacrament. Some, known as the Artotyrytae, as Augustine says (De Haeres. xxviii), "offer bread and cheese in this sacrament, contending that oblations were celebrated by men in the first ages, from fruits of the earth and sheep." Others, called Cataphrygae and Pepuziani, "are reputed to have made their Eucharistic bread with infants' blood drawn from tiny punctures over the entire body, and mixed with flour." Others, styled Aquarii, under guise of sobriety, offer nothing but water in this sacrament.Now all these and similar errors are excluded by the fact that Christ instituted this sacrament under the species of bread and wine, as is evident from Mt 26. Consequently, bread and wine are the proper matter of this sacrament. And the reasonableness of this is seen first, in the use of this sacrament, which is eating: for, as water is used in the sacrament of Baptism for the purpose of spiritual cleansing, since bodily cleansing is commonly done with water; so bread and wine, wherewith men are commonly fed, are employed in this sacrament for the use of spiritual eating.Secondly, in relation to Christ's Passion, in which the blood was separated from the body. And therefore in this sacrament, which is the memorial of our Lord's Passion, the bread is received apart as the sacrament of the body, and the wine as the sacrament of the blood.Thirdly, as to the effect, considered in each of the partakers. For, as Ambrose (Mag. Sent. iv, D, xi) says on 1Co 11,20, this sacrament "avails for the defense of soul and body"; and therefore "Christ's body is offered" under the species of bread "for the health of the body, and the blood" under the species of wine "for the health of the soul," according to Lv 17,14: "The life of the animal [Vulg.: 'of all flesh'] is in the blood."Fourthly, as to the effect with regard to the whole Church, which is made up of many believers, just "as bread is composed of many grains, and wine flows from many grapes," as the gloss observes on 1Co 10,17: "We being many are . . . one body," etc.
Reply to Objection: 1. Although the flesh of slaughtered animals represents the Passion more forcibly, nevertheless it is less suitable for the common use of this sacrament, and for denoting the unity of the Church.
2. Although wheat and wine are not produced in every country, yet they can easily be conveyed to every land, that is, as much as is needful for the use of this sacrament: at the same time one is not to be consecrated when the other is lacking, because it would not be a complete sacrament.
3. Wine taken in small quantity cannot do the sick much harm: yet if there be fear of harm, it is not necessary for all who take Christ's body to partake also of His blood, as will be stated later (Question , Article ).
Objection: 1. It seems that a determinate quantity of bread and wine is required for the matter of this sacrament. Because the effects of grace are no less set in order than those of nature. But, "there is a limit set by nature upon all existing things, and a reckoning of size and development" (De Anima ii). Consequently, in this sacrament, which is called "Eucharist," that is, "a good grace," a determinate quantity of the bread and wine is required.
2. Further, Christ gave no power to the ministers of the Church regarding matters which involve derision of the faith and of His sacraments, according to 2Co 10,8: "Of our power which the Lord hath given us unto edification, and not for your destruction." But it would lead to mockery of this sacrament if the priest were to wish to consecrate all the bread which is sold in the market and all the wine in the cellar. Therefore he cannot do this.
3. Further, if anyone be baptized in the sea, the entire sea-water is not sanctified by the form of baptism, but only the water wherewith the body of the baptized is cleansed. Therefore, neither in this sacrament can a superfluous quantity of bread be consecrated.
On the contrary Much is opposed to little, and great to small. But there is no quantity, however small, of the bread and wine which cannot be consecrated. Therefore, neither is there any quantity, however great, which cannot be consecrated.
I answer that Some have maintained that the priest could not consecrate an immense quantity of bread and wine, for instance, all the bread in the market or all the wine in a cask. But this does not appear to be true, because in all things containing matter, the reason for the determination of the matter is drawn from its disposition to an end, just as the matter of a saw is iron, so as to adapt it for cutting. But the end of this sacrament is the use of the faithful. Consequently, the quantity of the matter of this sacrament must be determined by comparison with the use of the faithful. But this cannot be determined by comparison with the use of the faithful who are actually present; otherwise the parish priest having few parishioners could not consecrate many hosts. It remains, then, for the matter of this sacrament to be determined in reference to the number of the faithful absolutely. But the number of the faithful is not a determinate one. Hence it cannot be said that the quantity of the matter of this sacrament is restricted.
Reply to Objection: 1. The matter of every natural object has its determinate quantity by comparison with its determinate form. But the number of the faithful, for whose use this sacrament is ordained, is not a determinate one. Consequently there is no comparison.
2. The power of the Church's ministers is ordained for two purposes: first for the proper effect, and secondly for the end of the effect. But the second does not take away the first. Hence, if the priest intends to consecrate the body of Christ for an evil purpose, for instance, to make mockery of it, or to administer poison through it, he commits sin by his evil intention, nevertheless, on account of the power committed to him, he accomplishes the sacrament.
3. The sacrament of Baptism is perfected in the use of the matter: and therefore no more of the water is hallowed than what is used. But this sacrament is wrought in the consecration of the matter. Consequently there is no parallel.
Objection: 1. It seems that wheaten bread is not requisite for the matter of this sacrament, because this sacrament is a reminder of our Lord's Passion. But barley bread seems to be more in keeping with the Passion than wheaten bread, as being more bitter, and because Christ used it to feed the multitudes upon the mountain, as narrated in Jn 6. Therefore wheaten bread is not the proper matter of this sacrament.
2. Further, in natural things the shape is a sign of species. But some cereals resemble wheat, such as spelt and maize, from which in some localities bread is made for the use of this sacrament. Therefore wheaten bread is not the proper matter of this sacrament.
3. Further, mixing dissolves species. But wheaten flour is hardly to be found unmixed with some other species of grain, except in the instance of specially selected grain. Therefore it does not seem that wheaten bread is the proper matter for this sacrament.
4. Further, what is corrupted appears to be of another species. But some make the sacrament from bread which is corrupted, and which no longer seems to be wheaten bread. Therefore, it seems that such bread is not the proper matter of this sacrament.
On the contrary Christ is contained in this sacrament, and He compares Himself to a grain of wheat, saying (Jn 12,24): "Unless the grain of wheat falling into the ground die, itself remaineth alone." Therefore bread from corn, i.e. wheaten bread, is the matter of this sacrament.
I answer that As stated above (Article ), for the use of the sacraments such matter is adopted as is commonly made use of among men. Now among other breads wheaten bread is more commonly used by men; since other breads seem to be employed when this fails. And consequently Christ is believed to have instituted this sacrament under this species of bread. Moreover this bread strengthens man, and so it denotes more suitably the effect of this sacrament. Consequently, the proper matter for this sacrament is wheaten bread.
Reply to Objection: 1. Barley bread serves to denote the hardness of the Old Law; both on account of the hardness of the bread, and because, as Augustine says (Question ): "The flour within the barley, wrapped up as it is within a most tenacious fibre, denotes either the Law itself, which was given in such manner as to be vested in bodily sacraments; or else it denotes the people themselves, who were not yet despoiled of carnal desires, which clung to their hearts like fibre." But this sacrament belongs to Christ's "sweet yoke," and to the truth already manifested, and to a spiritual people. Consequently barley bread would not be a suitable matter for this sacrament.
2. A begetter begets a thing like to itself in species. yet there is some unlikeness as to the accidents, owing either to the matter, or to weakness within the generative power. And therefore, if there be any cereals which can be grown from the seed of the wheat (as wild wheat from wheat seed grown in bad ground), the bread made from such grain can be the matter of this sacrament: and this does not obtain either in barley, or in spelt, or even in maize, which is of all grains the one most resembling the wheat grain. But the resemblance as to shape in such seems to denote closeness of species rather than identity; just as the resemblance in shape between the dog and the wolf goes to show that they are allied but not of the same species. Hence from such grains, which cannot in any way be generated from wheat grain, bread cannot be made such as to be the proper matter of this sacrament.
3. A moderate mixing does not alter the species, because that little is as it were absorbed by the greater. Consequently, then, if a small quantity of another grain be mixed with a much greater quantity of wheat, bread may be made therefrom so as to be the proper matter of this sacrament; but if the mixing be notable, for instance, half and half; or nearly so, then such mixing alters the species; consequently, bread made therefrom will not be the proper matter of this sacrament.
4. Sometimes there is such corruption of the bread that the species of bread is lost, as when the continuity of its parts is destroyed, and the taste, color, and other accidents are changed; hence the body of Christ may not be made from such matter. But sometimes there is not such corruption as to alter the species, but merely disposition towards corruption, which a slight change in the savor betrays, and from such bread the body of Christ may be made: but he who does so, sins from irreverence towards the sacrament. And because starch comes of corrupted wheat, it does not seem as if the body of Christ could be made of the bread made therefrom, although some hold the contrary.
Objection: 1. It seems that this sacrament ought not to be made of unleavened bread. because in this sacrament we ought to imitate Christ's institution. But Christ appears to have instituted this sacrament in fermented bread, because, as we have read in Ex 12, the Jews, according to the Law, began to use unleavened bread on the day of the Passover which is celebrated on the fourteenth day of the moon; and Christ instituted this sacrament at the supper which He celebrated "before the festival day of the Pasch" (Jn 13,1 Jn 13,4). Therefore we ought likewise to celebrate this sacrament with fermented bread.
2. Further, legal observances ought not to be continued in the time of grace. But the use of unleavened bread was a ceremony of the Law, as is clear from Ex 12. Therefore we ought not to use unfermented bread in this sacrament of grace.
3. Further, as stated above (Question , Article ; Question , Article ), the Eucharist is the sacrament of charity just as Baptism is the sacrament of faith. But the fervor of charity is signified by fermented bread, as is declared by the gloss on Mt 13,33: "The kingdom of heaven is like unto leaven," etc. Therefore this sacrament ought to be made of leavened bread.
4. Further, leavened or unleavened are mere accidents of bread, which do not vary the species. But in the matter for the sacrament of Baptism no difference is observed regarding the variation of the accidents, as to whether it be salt or fresh, warm or cold water. Therefore neither ought any distinction to be observed, as to whether the bread be unleavened or leavened.
On the contrary According to the Decretals (Extra, De Celebr. Miss.), a priest is punished "for presuming to celebrate, using fermented bread and a wooden cup."
I answer that Two things may be considered touching the matter of this sacrament namely, what is necessary, and what is suitable. It is necessary that the bread be wheaten, without which the sacrament is not valid, as stated above (Article ). It is not, however, necessary for the sacrament that the bread be unleavened or leavened, since it can be celebrated in either.But it is suitable that every priest observe the rite of his Church in the celebration of the sacrament. Now in this matter there are various customs of the Churches: for, Gregory says: "The Roman Church offers unleavened bread, because our Lord took flesh without union of sexes: but the Greek Churches offer leavened bread, because the Word of the Father was clothed with flesh; as leaven is mixed with the flour." Hence, as a priest sins by celebrating with fermented bread in the Latin Church, so a Greek priest celebrating with unfermented bread in a church of the Greeks would also sin, as perverting the rite of his Church. Nevertheless the custom of celebrating with unleavened bread is more reasonable. First, on account of Christ's institution: for He instituted this sacrament "on the first day of the Azymes" (Mt 26,17 Mc 14,12 Lc 22,7), on which day there ought to be nothing fermented in the houses of the Jews, as is stated in Ex 12,15 Ex 12,19. Secondly, because bread is properly the sacrament of Christ's body, which was conceived without corruption, rather than of His Godhead, as will be seen later (Question , Article , ad 1). Thirdly, because this is more in keeping with the sincerity of the faithful, which is required in the use of this sacrament, according to 1Co 5,7: "Christ our Pasch is sacrificed: therefore let us feast . . . with the unleavened bread of sincerity and truth."However, this custom of the Greeks is not unreasonable both on account of its signification, to which Gregory refers, and in detestation of the heresy of the Nazarenes, who mixed up legal observances with the Gospel.
Reply to Objection: 1. As we read in Ex 12, the paschal solemnity began on the evening of the fourteenth day of the moon. So, then, after immolating the Paschal Lamb, Christ instituted this sacrament: hence this day is said by John to precede the day of the Pasch, while the other three Evangelists call it "the first day of the Azymes," when fermented bread was not found in the houses of the Jews, as stated above. Fuller mention was made of this in the treatise on our Lord's Passion (Question , Article , ad 1).
2. Those who celebrate the sacrament with unleavened bread do not intend to follow the ceremonial of the Law, but to conform to Christ's institution; so they are not Judaizing; otherwise those celebrating in fermented bread would be Judaizing, because the Jews offered up fermented bread for the first-fruits.
3. Leaven denotes charity on account of one single effect, because it makes the bread more savory and larger; but it also signifies corruption from its very nature.
4. Since whatever is fermented partakes of corruption, this sacrament may not be made from corrupt bread, as stated above (Article , ad 4); consequently, there is a wider difference between unleavened and leavened bread than between warm and cold baptismal water: because there might be such corruption of fermented bread that it could not be validly used for the sacrament.
Objection: 1. It seems that wine of the grape is not the proper matter of this sacrament. Because, as water is the matter of Baptism, so is wine the matter of this sacrament. But Baptism can be conferred with any kind of water. Therefore this sacrament can be celebrated in any kind of wine, such as of pomegranates, or of mulberries; since vines do not grow in some countries.
2. Further, vinegar is a kind of wine drawn from the grape, as Isidore says (Etym. xx). But this sacrament cannot be celebrated with vinegar. Therefore, it seems that wine from the grape is not the proper matter of this sacrament.
3. Further, just as the clarified wine is drawn from grapes, so also are the juice of unripe grapes and must. But it does not appear that this sacrament may be made from such, according to what we read in the Sixth Council (Trull., Can. 28): "We have learned that in some churches the priests add grapes to the sacrifice of the oblation; and so they dispense both together to the people. Consequently we give order that no priest shall do this in future." And Pope Julius I rebukes some priests "who offer wine pressed from the grape in the sacrament of the Lord's chalice." Consequently, it seems that wine from the grape is not the proper matter of this sacrament.
On the contrary As our Lord compared Himself to the grain of wheat, so also He compared Himself to the vine, saying (Jn 15,1): "I am the true vine." But only bread from wheat is the matter of this sacrament, as stated above (Article ). Therefore, only wine from the grape is the proper matter of this sacrament.
I answer that This sacrament can only be performed with wine from the grape. First of all on account of Christ's institution, since He instituted this sacrament in wine from the grape, as is evident from His own words, in instituting this sacrament (Mt 26,29): "I will not drink from henceforth of this fruit of the vine." Secondly, because, as stated above (Article ), that is adopted as the matter of the sacraments which is properly and universally considered as such. Now that is properly called wine, which is drawn from the grape, whereas other liquors are called wine from resemblance to the wine of the grape. Thirdly, because the wine from the grape is more in keeping with the effect of this sacrament, which is spiritual; because it is written (Ps 103,15): "That wine may cheer the heart of man."
Reply to Objection: 1. Such liquors are called wine, not properly but only from their resemblance thereto. But genuine wine can be conveyed to such countries wherein the grape-vine does not flourish, in a quantity sufficient for this sacrament.
2. Wine becomes vinegar by corruption; hence there is no returning from vinegar to wine, as is said in Metaph. viii. And consequently, just as this sacrament may not be made from bread which is utterly corrupt, so neither can it be made from vinegar. It can, however, be made from wine which is turning sour, just as from bread turning corrupt, although he who does so sins, as stated above (Article ).
3. The juice of unripe grapes is at the stage of incomplete generation, and therefore it has not yet the species of wine: on which account it may not be used for this sacrament. Must, however, has already the species of wine, for its sweetness [*"Aut dulcis musti Vulcano decoquit humorem"; Virgil, Georg. i, 295] indicates fermentation which is "the result of its natural heat" (Meteor. iv); consequently this sacrament can be made from must. Nevertheless entire grapes ought not to be mixed with this sacrament, because then there would be something else besides wine. It is furthermore forbidden to offer must in the chalice, as soon as it has been squeezed from the grape, since this is unbecoming owing to the impurity of the must. But in case of necessity it may be done: for it is said by the same Pope Julius, in the passage quoted in the argument: "If necessary, let the grape be pressed into the chalice."
Objection: 1. It seems that water ought not to be mixed with the wine, since Christ's sacrifice was foreshadowed by that of Melchisedech, who (Gn 14,18) is related to have offered up bread and wine only. Consequently it seems that water should not be added in this sacrament.
2. Further, the various sacraments have their respective matters. But water is the matter of Baptism. Therefore it should not be employed as the matter of this sacrament.
3. Further, bread and wine are the matter of this sacrament. But nothing is added to the bread. Therefore neither should anything be added to the wine.
On the contrary Pope Alexander I writes ( omnes orth.): "In the sacramental oblations which in mass are offered to the Lord, only bread and wine mixed with water are to be offered in sacrifice."
I answer that Water ought to be mingled with the wine which is offered in this sacrament. First of all on account of its institution: for it is believed with probability that our Lord instituted this sacrament in wine tempered with water according to the custom of that country: hence it is written (Pr 9,5): "Drink the wine which I have mixed for you." Secondly, because it harmonizes with the representation of our Lord's Passion: hence Pope Alexander I says ( omnes orth.): "In the Lord's chalice neither wine only nor water only ought to be offered, but both mixed because we read that both flowed from His side in the Passion." Thirdly, because this is adapted for signifying the effect of this sacrament, since as Pope Julius says (Concil. Bracarens iii, Can. 1): "We see that the people are signified by the water, but Christ's blood by the wine. Therefore when water is mixed with the wine in the chalice, the people is made one with Christ." Fourthly, because this is appropriate to the fourth effect of this sacrament, which is the entering into everlasting life: hence Ambrose says (De Sacram. v): "The water flows into the chalice, and springs forth unto everlasting life."
Reply to Objection: 1. As Ambrose says (De Sacram. v), just as Christ's sacrifice is denoted by the offering of Melchisedech, so likewise it is signified by the water which flowed from the rock in the desert, according to 1Co 10,4: "But they drank of the spiritual rock which came after them."
2. In Baptism water is used for the purpose of ablution: but in this sacrament it is used by way of refreshment, according to Ps 22,3: "He hath brought me up on the water of refreshment."
3. Bread is made of water and flour; and therefore, since water is mixed with the wine, neither is without water.
Objection: 1. It seems that the mixing with water is essential to this sacrament. Because Cyprian says to Cecilius (Ep. lxiii): "Thus the Lord's chalice is not water only and wine only, but both must be mixed together: in the same way as neither the Lord's body be of flour only, except both," i.e. the flour and the water "be united as one." But the admixture of water with the flour is necessary for this sacrament. Consequently, for the like reason, so is the mixing of water with the wine.
2. Further, at our Lord's Passion, of which this is the memorial, water as well as blood flowed from His side. But wine, which is the sacrament of the blood, is necessary for this sacrament. For the same reason, therefore, so is water.
3. Further, if water were not essential to this sacrament, it would not matter in the least what kind of water was used; and so water distilled from roses, or any other kind might be employed; which is contrary to the usage of the Church. Consequently water is essential to this sacrament.
On the contrary Cyprian says (Ep. lxiii): "If any of our predecessors, out of ignorance or simplicity, has not kept this usage," i.e. of mixing water with the wine, "one may pardon his simplicity"; which would not be the case if water were essential to the sacrament, as the wine or the bread. Therefore the mingling of water with the wine is not essential to the sacrament.
I answer that Judgment concerning a sign is to be drawn from the thing signified. Now the adding of water to the wine is for the purpose of signifying the sharing of this sacrament by the faithful, in this respect that by the mixing of the water with the wine is signified the union of the people with Christ, as stated (Article ). Moreover, the flowing of water from the side of Christ hanging on the cross refers to the same, because by the water is denoted the cleansing from sins, which was the effect of Christ's Passion. Now it was observed above (Question , Article , ad 3), that this sacrament is completed in the consecration of the matter: while the usage of the faithful is not essential to the sacrament, but only a consequence thereof. Consequently, then, the adding of water is not essential to the sacrament.
Reply to Objection: 1. Cyprian's expression is to be taken in the same sense in which we say that a thing cannot be, which cannot be suitably. And so the comparison refers to what ought to be done, not to what is essential to be done; since water is of the essence of bread, but not of the essence of wine.
2. The shedding of the blood belonged directly to Christ's Passion: for it is natural for blood to flow from a wounded human body. But the flowing of the water was not necessary for the Passion; but merely to show its effect, which is to wash away sins, and to refresh us from the heat of concupiscence. And therefore the water is not offered apart from the wine in this sacrament, as the wine is offered apart from the bread; but the water is offered mixed with the wine to show that the wine belongs of itself to this sacrament, as of its very essence; but the water as something added to the wine.
3. Since the mixing of water with the wine is not necessary for the sacrament, it does not matter, as to the essence of the sacrament, what kind of water is added to the wine, whether natural water, or artificial, as rose-water, although, as to the propriety of the sacrament, he would sin who mixes any other than natural and true water, because true water flowed from the side of Christ hanging on the cross, and not phlegm, as some have said, in order to show that Christ's body was truly composed of the four elements; as by the flowing blood, it was shown to be composed of the four humors, as Pope Innocent III says in a certain Decree. But because the mixing of water with flour is essential to this sacrament, as making the composition of bread, if rose-water, or any other liquor besides true water, be mixed with the flour, the sacrament would not be valid, because it would not be true bread.
Summa Th. III EN Qu.73 a.6