However, the belief that the Seven Sacraments are equally great is condemned by the Ecumenical Council of Trent:
Si quis dixerit haec septem sacramenta ita esse inter se paria ut nulla ratione aliud sit alio dignius; anathema sit.
If any one saith, that these seven sacraments are in such wise equal to each other, as that one is not in any way more worthy than another; let him be anathema.
Since the Ecumenical Council of Trent makes the point crystal clear, the next question immediately follows: Which Sacrament is the greatest? There are different arguments, and they seem convincing one way or another.
One argument is that Baptism is the greatest Sacrament, because as the Catechism of the Council of Trent taught, the sixth effect of Baptism is "Opening the Gates of Heaven", which means without Baptism, including Baptism of Desire and Baptism of Blood, no one can enter the Kingdom of Heaven., and only after Baptism, a person can become a Christian and receive other Sacraments. One may also argue that Confirmation is the greatest Sacrament, because only after this Sacrament, a faithful can receive the Seven Gifts of the Holy Gift and become a Solider of Christ.
Another argument is that Penance is the greatest Sacrament, because without Penance, faithfuls are not allowed to receive Eucharist and mortal sins cannot be forgiven, because faithfuls cannot enter the Kingdom of Heaven without the forgiveness of mortal sins, unless a person can maintain a life so holy that it is never stained by mortal sins. A similar argument is that Unction is the greatest Sacrament, because it is the Sacrament to prepare for a person's death.
It is also reasonable to say that Matrimony is the greatest Sacrament, for without Matrimony (at least marriage in the secular sense), human will either go extinct or have to become fornicators, and their will be no one to confer Sacraments. Similarly, it is also understandable to argue that Orders is the greatest Sacrament, because without this apostolic succession, there will be no one eligible to confer any Sacraments in the future generations.
However, all the aforementioned arguments are entrenched in the same flaw that precedence before the consequent results is equated with greatness. However, if being asked to define what means to be the "greatest", people will answer "the most noble", "the most respected", "the most powerful", etc, but no one will say something is the greatest simply because it happens first and causes the others. (However, this is not to be confused with the First Cause in the philosophical sense, and they are two entirely different things.)
The definition of "greatest" clearly indicates an extraordinary intrinsic value, and such a value can be manifested in many ways, such as power, achievement, and dignity. When comparing the Seven Sacraments, we can see all of them are channels of the divine grace, but none of them can single-handedly guarantee our eternal and greatest reward. Therefore, we cannot distinguish any Sacrament from the others based on power or achievement. Therefore, it is reasonable to compare them based on dignity.
From this perspective, we can easily see that Eucharist is the greatest Sacrament, but Eucharist has the highest dignity. For the other Sacraments, such as Baptism and Confirmation, after the ceremony, water is still water and oil is still oil. But for Eucharist, after the ceremony, Bread and Wine become the Body, Blood, Soul and Divinity of Jesus Christ Our Lord.
But is Eucharist the greatest Sacrament because of transubstantiation only? Saint Thomas Aquinas, the Angelic and Common Doctor, gives his most comprehensive explanation, and has answered several objections in his monumental Summa Theologiae, Part 3, Question 65, Article 3.
Ad tertium sic proceditur. Videtur quod sacramentum Eucharistiae non sit potissimum inter sacramenta. Bonum enim commune potius est quam bonum unius, ut dicitur I Ethica. Sed matrimonium ordinatur ad bonum commune speciei humanae per viam generationis, sacramentum autem Eucharistiae ordinatur ad bonum proprium sumentis. Ergo non est potissimum sacramentorum.
Objection 1: It seems that the Eucharist is not the principal of the sacraments. For the common good is of more account than the good of the individual (I Ethic). But Matrimony is ordained to the common good of the human race by means of generation: whereas the sacrament of the Eucharist is ordained to the private good of the recipient. Therefore it is not the greatest of the sacraments.
Praeterea, digniora sacramenta esse videntur quae per maiorem ministrum conferuntur. Sed sacramentum confirmationis et sacramentum ordinis non conferuntur nisi per episcopum, qui est maior minister quam simplex minister, qui est sacerdos, per quem confertur Eucharistiae sacramentum. Ergo illa sacramenta sunt potiora.
Objection 2: Further, those sacraments, seemingly, are greater, which are conferred by a greater minister. But the sacraments of Confirmation and order are conferred by a bishop only, who is a greater minister than a mere minister such as a priest, by whom the sacraments of the Eucharist is conferred. Therefore those sacraments are greater.
Praeterea, sacramenta tanto sunt potiora quanto maiorem virtutem habent. Sed quaedam sacramenta imprimunt characterem, scilicet Baptismus, confirmatio et ordo, quod non facit Eucharistia. Ergo illa sacramenta sunt potiora.
Objection 3: Further, those Sacraments are greater that have the greater power. But some of the sacraments imprint a character, namely Baptism, Confirmation and order; whereas the Eucharist does not. Therefore those sacraments are greater.
Praeterea, illud videtur esse potius ex quo alia dependent et non e converso. Sed ex Baptismo dependet Eucharistia, non enim potest aliquis Eucharistiam accipere nisi fuerit baptizatus. Ergo Baptismus est potior Eucharistia.
Objection 4: Further, that seems to be greater, on which others depend without its depending on them. But the Eucharist depends on Baptism: since no one can receive the Eucharist except he has been baptized. Therefore Baptism is greater than the Eucharist.
Sed contra est quod Dionysius dicit, III caput, De Ecclesiastica Hierarchia, quod non contingit aliquem perfici perfectione hierarchica nisi per divinissimam Eucharistiam. Ergo hoc sacramentum potissimum et perfectivum est omnium aliorum.
On the contrary, Dionysius says (On the Ecclesiastical Hierarchy, III) that no one receives hierarchical perfection save by the most God-like Eucharist. Therefore this sacrament is greater than all the others and perfects them.
Respondeo dicendum quod, simpliciter loquendo, sacramentum Eucharistiae est potissimum inter alia sacramenta. Quod quidem tripliciter apparet. Primo quidem, ex eo quod in eo continetur ipse Christus substantialiter, in aliis autem sacramentis continetur quaedam virtus instrumentalis participata a Christo, ut ex supra dictis patet. Semper autem quod est per essentiam, potius est eo quod est per participationem.
I answer that, Absolutely speaking, the sacrament of the Eucharist is the greatest of all the sacraments: and this may be shown in three ways. First of all because it contains Christ Himself substantially: whereas the other sacraments contain a certain instrumental power which is a share of Christ’s power, as we have shown above. Now that which is essentially such is always of more account than that which is such by participation.
Secundo hoc apparet ex ordine sacramentorum ad invicem, nam omnia alia sacramenta ordinari videntur ad hoc sacramentum sicut ad finem. Manifestum est enim quod sacramentum ordinis ordinatur ad Eucharistiae consecrationem. Sacramentum vero Baptismi ordinatur ad Eucharistiae receptionem. In quo etiam perficitur aliquis per confirmationem, ut non vereatur se subtrahere a tali sacramento. Per poenitentiam etiam et extremam unctionem praeparatur homo ad digne sumendum corpus Christi. Matrimonium autem saltem sua significatione attingit hoc sacramentum, inquantum significat coniunctionem Christi et Ecclesiae, cuius unitas per sacramentum Eucharistiae figuratur, unde et apostolus dicit, Ephesios, V, sacramentum hoc magnum est, ego autem dico in Christo et in Ecclesia.
Second, this is made clear by considering the relation of the sacraments to one another. For all the other sacraments seem to be ordained to this one as to their end. For it is manifest that the sacrament of order is ordained to the consecration of the Eucharist: and the sacrament of Baptism to the reception of the Eucharist: while a man is perfected by Confirmation, so as not to fear to abstain from this sacrament. By Penance and Extreme Unction man is prepared to receive the Body of Christ worthily. And Matrimony at least in its signification, touches this sacrament; in so far as it signifies the union of Christ with the Church, of which union the Eucharist is a figure: hence the Apostle says (Ephesians, 5): This is a great sacrament: but I speak in Christ and in the Church.
Tertio hoc apparet ex ritu sacramentorum. Nam fere omnia sacramenta in Eucharistia consummantur, ut dicit Dionysius, III caput, De Ecclesiastica Hierarchia, sicut patet quod ordinati communicant, et etiam baptizati si sint adulti.
Third, this is made clear by considering the rites of the sacraments. For nearly all the sacraments terminate in the Eucharist, as Dionysius says (On the Ecclesiastical Hierarchy, III): thus those who have been ordained receive Holy Communion, as also do those who have been baptized, if they be adult.
Aliorum autem sacramentorum comparatio ad invicem potest esse multipliciter. Nam in via necessitatis, Baptismus est potissimum sacramentorum; in via autem perfectionis, sacramentum ordinis; medio autem modo se habet sacramentum confirmationis. Sacramentum vero poenitentiae et extremae unctionis sunt inferioris gradus a praedictis sacramentis, quia, sicut dictum est, ordinantur ad vitam Christianam non per se, sed quasi per accidens, scilicet in remedium supervenientis defectus. Inter quae tamen extrema unctio comparatur ad poenitentiam sicut confirmatio ad Baptismum, ita scilicet quod poenitentia est maioris necessitatis, sed extrema unctio est maioris perfectionis.
The remaining sacraments may be compared to one another in several ways. For on the ground of necessity, Baptism is the greatest of the sacraments; while from the point of view of perfection, order comes first; while Confirmation holds a middle place. The sacraments of Penance and Extreme Unction are on a degree inferior to those mentioned above; because, as stated above, they are ordained to the Christian life, not directly, but accidentally, as it were, that is to say, as remedies against supervening defects. And among these, Extreme Unction is compared to Penance, as Confirmation to Baptism; in such a way, that Penance is more necessary, whereas Extreme Unction is more perfect.
Ad primum ergo dicendum quod matrimonium ordinatur ad bonum commune corporaliter. Sed bonum commune spirituale totius Ecclesiae continetur substantialiter in ipso Eucharistiae sacramento.
Reply Objection 1: Matrimony is ordained to the common good as regards the body. But the common spiritual good of the whole Church is contained substantially in the sacrament itself of the Eucharist.
Ad secundum dicendum quod per ordinem et confirmationem deputantur fideles Christi ad aliqua specialia officia, quod pertinet ad officium principis. Et ideo tradere huiusmodi sacramenta pertinet ad solum episcopum, qui est quasi princeps in Ecclesia. Per sacramentum vero Eucharistiae non deputatur homo ad aliquod officium, sed magis hoc sacramentum est finis omnium officiorum, ut dictum est.
Reply Objection 2: By Order and Confirmation the faithful of Christ are deputed to certain special duties; and this can be done by the prince alone. Consequently the conferring of these sacraments belongs exclusively to a Bishop, who is, as it were, a prince in the Church. But a man is not deputed to any duty by the Sacrament of the Eucharist, rather is this Sacrament the end of all duties, as stated above.
Ad tertium dicendum quod character sacramentalis, sicut supra dictum est, quaedam participatio est sacerdotii Christi. Unde sacramentum quod ipsum Christum coniungit homini, est dignius sacramento quod imprimit Christi characterem.
Reply Objection 3: The sacramental character, as stated above, is a kind of participation in Christ’s priesthood. Wherefore the Sacrament that unites man to Christ Himself, is greater than a sacrament that imprints Christ’s character.
Ad quartum dicendum quod ratio illa procedit ex parte necessitatis. Sic enim Baptismus, cum sit maximae necessitatis, est potissimum sacramentorum. Sicut ordo et confirmatio habent quandam excellentiam ratione ministerii; et matrimonium ratione significationis. Nihil enim prohibet aliquid esse secundum quid dignius, quod tamen non est dignius simpliciter.
Reply Objection 4: This argument proceeds on the ground of necessity. For thus Baptism, being of the greatest necessity, is the greatest of the sacraments, just as Order and Confirmation have a certain excellence considered in their administration; and Matrimony by reason of its signification. For there is no reason why a thing should not be greater from a certain point of view which is not greater absolutely speak.
Here, we can see the threefold reasons why Eucharist is the greatest Sacrament:
(1) Eucharist contains Christ Himself substantially;
(2) All the other Sacraments are instituted for Eucharist as their end;
(3) All the other Sacraments terminate at Eucharist.
Since the Ecumenical Council of Trent makes the point crystal clear, the next question immediately follows: Which Sacrament is the greatest? There are different arguments, and they seem convincing one way or another.
One argument is that Baptism is the greatest Sacrament, because as the Catechism of the Council of Trent taught, the sixth effect of Baptism is "Opening the Gates of Heaven", which means without Baptism, including Baptism of Desire and Baptism of Blood, no one can enter the Kingdom of Heaven., and only after Baptism, a person can become a Christian and receive other Sacraments. One may also argue that Confirmation is the greatest Sacrament, because only after this Sacrament, a faithful can receive the Seven Gifts of the Holy Gift and become a Solider of Christ.
Another argument is that Penance is the greatest Sacrament, because without Penance, faithfuls are not allowed to receive Eucharist and mortal sins cannot be forgiven, because faithfuls cannot enter the Kingdom of Heaven without the forgiveness of mortal sins, unless a person can maintain a life so holy that it is never stained by mortal sins. A similar argument is that Unction is the greatest Sacrament, because it is the Sacrament to prepare for a person's death.
It is also reasonable to say that Matrimony is the greatest Sacrament, for without Matrimony (at least marriage in the secular sense), human will either go extinct or have to become fornicators, and their will be no one to confer Sacraments. Similarly, it is also understandable to argue that Orders is the greatest Sacrament, because without this apostolic succession, there will be no one eligible to confer any Sacraments in the future generations.
However, all the aforementioned arguments are entrenched in the same flaw that precedence before the consequent results is equated with greatness. However, if being asked to define what means to be the "greatest", people will answer "the most noble", "the most respected", "the most powerful", etc, but no one will say something is the greatest simply because it happens first and causes the others. (However, this is not to be confused with the First Cause in the philosophical sense, and they are two entirely different things.)
The definition of "greatest" clearly indicates an extraordinary intrinsic value, and such a value can be manifested in many ways, such as power, achievement, and dignity. When comparing the Seven Sacraments, we can see all of them are channels of the divine grace, but none of them can single-handedly guarantee our eternal and greatest reward. Therefore, we cannot distinguish any Sacrament from the others based on power or achievement. Therefore, it is reasonable to compare them based on dignity.
From this perspective, we can easily see that Eucharist is the greatest Sacrament, but Eucharist has the highest dignity. For the other Sacraments, such as Baptism and Confirmation, after the ceremony, water is still water and oil is still oil. But for Eucharist, after the ceremony, Bread and Wine become the Body, Blood, Soul and Divinity of Jesus Christ Our Lord.
In fact, even only by browsing the tables of contents of theological treatises and manuals, we find in many places, the great theologians of the Holy Catholic Church have used the unique styles "De Sanctissima Eucharistia" (Tractatus Canonicus, Cardinal Pietro Gasparii, Praelectiones Dogmaticae, Father Christian Pesch, Manuale Theologiae Dogmaticae, Father Jean Marie Herve, Theologiae Moralis, Father Arthur Vermeersch), "Tractatus de Sanctissima Eucharistia" (Tractatus Dogmatici, Father Edouard Hugon, Summa Theologiae Moralis, Father Henry Benedict Merkelbach), "De Sanctissimo Eucharistiae Sacramento" (De Ecclesiae Sacramentis, Cardinal Louis Bilot), "De Sanctissima Eucharistiae est Sacramentum" (Manuale Theologiae Moralis, Father Dominic Prümmer), "De Sacramento Unitatis Christianae seu de Sanctissima Eucharistia/On the Sacrament of Christian Unity or on the Most Holy Eucharist" (Sacrae Theologiae Summa, Spanish Jesuit Fathers), "De Sanctissimo Eucharistiae Sacramento et Sacrificio" (De Sacramentis, Cardinal Johann Baptise Franzelin), "Tractatus de Augustissimo Eucharistiae Sacramento" (Praelectiones Theologicae, Father Giovanni Perrone, Theologiae Polemicae, Spanish Jesuit Fathers), "De Sanctissimo Communione seu de Sacramento Eucharistiae" (Manuale Theologiae Moralis, Father Hermes Peeters), and "On the Most Holy Eucharist" (Doctrina Christiana, Cardinal Saint Robert Francisco Romolo Bellarmine). Over and over, we can see this superlative style has appeared in even catechisms, and this style is reserved exclusively for Eucharist. Thus, it is clear that it is common among theologians to distinguish Eucharist as the greatest Sacrament from the other Sacraments.
But is Eucharist the greatest Sacrament because of transubstantiation only? Saint Thomas Aquinas, the Angelic and Common Doctor, gives his most comprehensive explanation, and has answered several objections in his monumental Summa Theologiae, Part 3, Question 65, Article 3.
Ad tertium sic proceditur. Videtur quod sacramentum Eucharistiae non sit potissimum inter sacramenta. Bonum enim commune potius est quam bonum unius, ut dicitur I Ethica. Sed matrimonium ordinatur ad bonum commune speciei humanae per viam generationis, sacramentum autem Eucharistiae ordinatur ad bonum proprium sumentis. Ergo non est potissimum sacramentorum.
Objection 1: It seems that the Eucharist is not the principal of the sacraments. For the common good is of more account than the good of the individual (I Ethic). But Matrimony is ordained to the common good of the human race by means of generation: whereas the sacrament of the Eucharist is ordained to the private good of the recipient. Therefore it is not the greatest of the sacraments.
Praeterea, digniora sacramenta esse videntur quae per maiorem ministrum conferuntur. Sed sacramentum confirmationis et sacramentum ordinis non conferuntur nisi per episcopum, qui est maior minister quam simplex minister, qui est sacerdos, per quem confertur Eucharistiae sacramentum. Ergo illa sacramenta sunt potiora.
Objection 2: Further, those sacraments, seemingly, are greater, which are conferred by a greater minister. But the sacraments of Confirmation and order are conferred by a bishop only, who is a greater minister than a mere minister such as a priest, by whom the sacraments of the Eucharist is conferred. Therefore those sacraments are greater.
Praeterea, sacramenta tanto sunt potiora quanto maiorem virtutem habent. Sed quaedam sacramenta imprimunt characterem, scilicet Baptismus, confirmatio et ordo, quod non facit Eucharistia. Ergo illa sacramenta sunt potiora.
Objection 3: Further, those Sacraments are greater that have the greater power. But some of the sacraments imprint a character, namely Baptism, Confirmation and order; whereas the Eucharist does not. Therefore those sacraments are greater.
Praeterea, illud videtur esse potius ex quo alia dependent et non e converso. Sed ex Baptismo dependet Eucharistia, non enim potest aliquis Eucharistiam accipere nisi fuerit baptizatus. Ergo Baptismus est potior Eucharistia.
Objection 4: Further, that seems to be greater, on which others depend without its depending on them. But the Eucharist depends on Baptism: since no one can receive the Eucharist except he has been baptized. Therefore Baptism is greater than the Eucharist.
Sed contra est quod Dionysius dicit, III caput, De Ecclesiastica Hierarchia, quod non contingit aliquem perfici perfectione hierarchica nisi per divinissimam Eucharistiam. Ergo hoc sacramentum potissimum et perfectivum est omnium aliorum.
On the contrary, Dionysius says (On the Ecclesiastical Hierarchy, III) that no one receives hierarchical perfection save by the most God-like Eucharist. Therefore this sacrament is greater than all the others and perfects them.
Respondeo dicendum quod, simpliciter loquendo, sacramentum Eucharistiae est potissimum inter alia sacramenta. Quod quidem tripliciter apparet. Primo quidem, ex eo quod in eo continetur ipse Christus substantialiter, in aliis autem sacramentis continetur quaedam virtus instrumentalis participata a Christo, ut ex supra dictis patet. Semper autem quod est per essentiam, potius est eo quod est per participationem.
I answer that, Absolutely speaking, the sacrament of the Eucharist is the greatest of all the sacraments: and this may be shown in three ways. First of all because it contains Christ Himself substantially: whereas the other sacraments contain a certain instrumental power which is a share of Christ’s power, as we have shown above. Now that which is essentially such is always of more account than that which is such by participation.
Secundo hoc apparet ex ordine sacramentorum ad invicem, nam omnia alia sacramenta ordinari videntur ad hoc sacramentum sicut ad finem. Manifestum est enim quod sacramentum ordinis ordinatur ad Eucharistiae consecrationem. Sacramentum vero Baptismi ordinatur ad Eucharistiae receptionem. In quo etiam perficitur aliquis per confirmationem, ut non vereatur se subtrahere a tali sacramento. Per poenitentiam etiam et extremam unctionem praeparatur homo ad digne sumendum corpus Christi. Matrimonium autem saltem sua significatione attingit hoc sacramentum, inquantum significat coniunctionem Christi et Ecclesiae, cuius unitas per sacramentum Eucharistiae figuratur, unde et apostolus dicit, Ephesios, V, sacramentum hoc magnum est, ego autem dico in Christo et in Ecclesia.
Second, this is made clear by considering the relation of the sacraments to one another. For all the other sacraments seem to be ordained to this one as to their end. For it is manifest that the sacrament of order is ordained to the consecration of the Eucharist: and the sacrament of Baptism to the reception of the Eucharist: while a man is perfected by Confirmation, so as not to fear to abstain from this sacrament. By Penance and Extreme Unction man is prepared to receive the Body of Christ worthily. And Matrimony at least in its signification, touches this sacrament; in so far as it signifies the union of Christ with the Church, of which union the Eucharist is a figure: hence the Apostle says (Ephesians, 5): This is a great sacrament: but I speak in Christ and in the Church.
Tertio hoc apparet ex ritu sacramentorum. Nam fere omnia sacramenta in Eucharistia consummantur, ut dicit Dionysius, III caput, De Ecclesiastica Hierarchia, sicut patet quod ordinati communicant, et etiam baptizati si sint adulti.
Third, this is made clear by considering the rites of the sacraments. For nearly all the sacraments terminate in the Eucharist, as Dionysius says (On the Ecclesiastical Hierarchy, III): thus those who have been ordained receive Holy Communion, as also do those who have been baptized, if they be adult.
Aliorum autem sacramentorum comparatio ad invicem potest esse multipliciter. Nam in via necessitatis, Baptismus est potissimum sacramentorum; in via autem perfectionis, sacramentum ordinis; medio autem modo se habet sacramentum confirmationis. Sacramentum vero poenitentiae et extremae unctionis sunt inferioris gradus a praedictis sacramentis, quia, sicut dictum est, ordinantur ad vitam Christianam non per se, sed quasi per accidens, scilicet in remedium supervenientis defectus. Inter quae tamen extrema unctio comparatur ad poenitentiam sicut confirmatio ad Baptismum, ita scilicet quod poenitentia est maioris necessitatis, sed extrema unctio est maioris perfectionis.
The remaining sacraments may be compared to one another in several ways. For on the ground of necessity, Baptism is the greatest of the sacraments; while from the point of view of perfection, order comes first; while Confirmation holds a middle place. The sacraments of Penance and Extreme Unction are on a degree inferior to those mentioned above; because, as stated above, they are ordained to the Christian life, not directly, but accidentally, as it were, that is to say, as remedies against supervening defects. And among these, Extreme Unction is compared to Penance, as Confirmation to Baptism; in such a way, that Penance is more necessary, whereas Extreme Unction is more perfect.
Ad primum ergo dicendum quod matrimonium ordinatur ad bonum commune corporaliter. Sed bonum commune spirituale totius Ecclesiae continetur substantialiter in ipso Eucharistiae sacramento.
Reply Objection 1: Matrimony is ordained to the common good as regards the body. But the common spiritual good of the whole Church is contained substantially in the sacrament itself of the Eucharist.
Ad secundum dicendum quod per ordinem et confirmationem deputantur fideles Christi ad aliqua specialia officia, quod pertinet ad officium principis. Et ideo tradere huiusmodi sacramenta pertinet ad solum episcopum, qui est quasi princeps in Ecclesia. Per sacramentum vero Eucharistiae non deputatur homo ad aliquod officium, sed magis hoc sacramentum est finis omnium officiorum, ut dictum est.
Reply Objection 2: By Order and Confirmation the faithful of Christ are deputed to certain special duties; and this can be done by the prince alone. Consequently the conferring of these sacraments belongs exclusively to a Bishop, who is, as it were, a prince in the Church. But a man is not deputed to any duty by the Sacrament of the Eucharist, rather is this Sacrament the end of all duties, as stated above.
Ad tertium dicendum quod character sacramentalis, sicut supra dictum est, quaedam participatio est sacerdotii Christi. Unde sacramentum quod ipsum Christum coniungit homini, est dignius sacramento quod imprimit Christi characterem.
Reply Objection 3: The sacramental character, as stated above, is a kind of participation in Christ’s priesthood. Wherefore the Sacrament that unites man to Christ Himself, is greater than a sacrament that imprints Christ’s character.
Ad quartum dicendum quod ratio illa procedit ex parte necessitatis. Sic enim Baptismus, cum sit maximae necessitatis, est potissimum sacramentorum. Sicut ordo et confirmatio habent quandam excellentiam ratione ministerii; et matrimonium ratione significationis. Nihil enim prohibet aliquid esse secundum quid dignius, quod tamen non est dignius simpliciter.
Reply Objection 4: This argument proceeds on the ground of necessity. For thus Baptism, being of the greatest necessity, is the greatest of the sacraments, just as Order and Confirmation have a certain excellence considered in their administration; and Matrimony by reason of its signification. For there is no reason why a thing should not be greater from a certain point of view which is not greater absolutely speak.
Here, we can see the threefold reasons why Eucharist is the greatest Sacrament:
(1) Eucharist contains Christ Himself substantially;
(2) All the other Sacraments are instituted for Eucharist as their end;
(3) All the other Sacraments terminate at Eucharist.