o intend
to do what the Church does.

The other point to be considered is the meaning of the words. For
since in the sacraments, the words produce an effect according to the
sense which they convey, as stated above (A. 7, ad 1), we must see
whether the change of words destroys the essential sense of the
words: because then the sacrament is clearly rendered invalid. Now it
is clear, if any substantial part of the sacramental form be
suppressed, that the essential sense of the words is destroyed; and
consequently the sacrament is invalid. Wherefore Didymus says (De
Spir. Sanct. ii): "If anyone attempt to baptize in such a way as to
omit one of the aforesaid names," i.e. of the Father, Son, and Holy
Ghost, "his baptism will be invalid." But if that which is omitted be
not a substantial part of the form, such an omission does not destroy
the essential sense of the words, nor consequently the validity of
the sacrament. Thus in the form of the Eucharist--"For this is My
Body," the omission of the word "for" does not destroy the essential
sense of the words, nor consequently cause the sacrament to be
invalid; although perhaps he who makes the omission may sin from
negligence or contempt.

Again, it is possible to add something that destroys the essential
sense of the words: for instance, if one were to say: "I baptize thee
in the name of the Father Who is greater, and of the Son Who is
less," with which form the Arians baptized: and consequently such an
addition makes the sacrament invalid. But if the addition be such as
not to destroy the essential sense, the sacrament is not rendered
invalid. Nor does it matter whether this addition be made at the
beginning, in the middle, or at the end: For instance, if one were to
say, "I baptize thee in the name of the Father Almighty, and of the
only Begotten Son, and of the Holy Ghost, the Paraclete," the baptism
would be valid; and in like manner if one were to say, "I baptize
thee in the name of the Father, and of the Son, and of the Holy
Ghost; and may the Blessed Virgin succour thee," the baptism would be
valid.

Perhaps, however, if one were to say, "I baptize thee in the name of
the Father, and of the Son, and of the Holy Ghost, and of the Blessed
Virgin Mary," the baptism would be void; because it is written (1
Cor. 1:13): "Was Paul crucified for you or were you baptized in the
name of Paul?" But this is true if the intention be to baptize in the
name of the Blessed Virgin a