hat it does not belong to a priest to
catechize and exorcize the person to be baptized. For it belongs to
the office of ministers to operate on the unclean, as Dionysius says
(Eccl. Hier. v). But catechumens who are instructed by catechism, and
"energumens" who are cleansed by exorcism, are counted among the
unclean, as Dionysius says in the same place. Therefore to catechize
and to exorcize do not belong to the office of the priests, but
rather to that of the ministers.

Obj. 2: Further, catechumens are instructed in the Faith by the Holy
Scripture which is read in the church by ministers: for just as the
Old Testament is recited by the Readers, so the New Testament is read
by the Deacons and Subdeacons. And thus it belongs to the ministers
to catechize. In like manner it belongs, seemingly, to the ministers
to exorcize. For Isidore says (Epist. ad Ludifred.): "The exorcist
should know the exorcisms by heart, and impose his hands on the
energumens and catechumens during the exorcism." Therefore it belongs
not to the priestly office to catechize and exorcize.

Obj. 3: Further, "to catechize" is the same as "to teach," and this
is the same as "to perfect." Now this belongs to the office of a
bishop, as Dionysius says (Eccl. Hier. v). Therefore it does not
belong to the priestly office.

_On the contrary,_ Pope Nicolas I says: "The catechizing of those who
are to be baptized can be undertaken by the priests attached to each
church." And Gregory says (Hom. xxix super Ezech.): "When priests
place their hands on believers for the grace of exorcism, what else
do they but cast out the devils?"

_I answer that,_ The minister compared to the priest, is as a
secondary and instrumental agent to the principal agent: as is
implied in the very word "minister." Now the secondary agent does
nothing without the principal agent in operating. And the more mighty
the operation, so much the mightier instruments does the principal
agent require. But the operation of the priest in conferring the
sacrament itself is mightier than in those things that are
preparatory to the sacrament. And so the highest ministers who are
called deacons co-operate with the priest in bestowing the sacraments
themselves: for Isidore says (Epist. ad Ludifred.) that "it belongs
to the deacons to assist the priests in all things that are done in
Christ's sacraments, in Baptism, to wit, in the Chrism, in the Paten
and Chalice"; while the inferior ministers assist