Thomas Aquinas

“ And since a person acquires the proximate disposition to the Eucharist by being cleansed from sin, it follows that the priest is the proper minister of all those sacraments which are chiefly instituted for the cleansing of sins, namely Baptism, Penance, and Extreme Unction. ”

“ But because many things are directed to the Eucharist, as being the most exalted of the sacraments, it follows not unfittingly that one Order has many acts besides its principal act, and all the more, as it ranks higher, since a power extends to the more things, the higher it is.
Reply to Objection 1: The preparation of the recipients of a sacrament is twofold. One is remote and is effected by the ministers: another is proximate, whereby they are rendered apt at once for receiving the sacraments. ”

“ In the early Church, on account of the fewness of ministers, all the lower ministries were entrusted to the deacons, as Dionysius says (Eccl. Hier. iii) , where he says: "Some of the ministers stand at the closed door of the Church, others are otherwise occupied in the exercise of their own order; others place the sacred bread and the chalice of benediction on the altar and offer them to the priests." Nevertheless all the power to do all these things was included in the one power of the deacon, though implicitly. ”

“ By the imposition of hands the fulness of grace is given, whereby they are qualified for exalted duties, wherefore only deacons and priests receive the imposition of hands, because they are competent to dispense the sacraments, although the latter as principal dispensers, the former as ministers. But by the anointing they are consecrated for the purpose of handling the sacrament, wherefore the anointing is done to the priests alone who touch the body of Christ with their own hands; even as a chalice is anointed because it holds the blood, and the paten because it holds the body. ”

“ Further, in every act of a special Order, there should be some special power, which the person ordained has to the exclusion of other persons. But in opening and shutting doors the doorkeeper has no special power that other men have not. Therefore this should not be reckoned their act.
I answer that, Since the consecration conferred in the sacrament of orders is directed to the sacrament of the Eucharist, as stated above [4910] (A [2] ) , the principal act of each order is that whereby it is most nearly directed to the sacrament of the Eucharist. ”

“ In another way on the part of the whole Church, and thus the priest alone exercises acts immediately directed to God; because to impersonate the whole Church belongs to him alone who consecrates the Eucharist, which is the sacrament of the universal Church.
Reply to Objection 3: The offerings made by the people are offered through the priest. Hence a twofold ministry is necessary with regard to offerings. One on the part of the people: and this belongs to the subdeacon who receives the offerings from the people and places them on the altar or offers them to the deacon. ”

“ Further, by the sacrament of Order a man is appointed to dispense the other sacraments. But there are only six other sacraments. Therefore there should be only six Orders.
Objection 4: On the other hand, It would seem that there ought to be more. For the higher a power is, the less is it subject to multiplication. Now the hierarchical power is in the angels in a higher way than in us, as Dionysius says (Eccl. Hier. i) . Since then there are nine Orders in the angelic hierarchy, there should be as many, or more, in the Church. ”

“ Reply to Objection 2: Acts are directed immediately to God in two ways; in one way on the part of one person only, for instance the prayers of individuals, vows, and so forth: such acts befit any baptized person. ”