as the sacrament is complete. Therefore
it seems that in the sacraments there is no power for causing grace.

Obj. 4: Further, the same thing cannot be in several. But several
things concur in the completion of a sacrament, namely, words and
things: while in one sacrament there can be but one power. Therefore
it seems that there is no power of causing grace in the sacraments.

_On the contrary,_ Augustine says (Tract. lxxx in Joan.): "Whence
hath water so great power, that it touches the body and cleanses the
heart?" And Bede says that "Our Lord conferred a power of
regeneration on the waters by the contact of His most pure body."

_I answer that,_ Those who hold that the sacraments do not cause
grace save by a certain coincidence, deny the sacraments any power
that is itself productive of the sacramental effect, and hold that
the Divine power assists the sacraments and produces their effect.
But if we hold that a sacrament is an instrumental cause of grace, we
must needs allow that there is in the sacraments a certain
instrumental power of bringing about the sacramental effects. Now
such power is proportionate to the instrument: and consequently it
stands in comparison to the complete and perfect power of anything,
as the instrument to the principal agent. For an instrument, as
stated above (A. 1), does not work save as moved by the principal
agent, which works of itself. And therefore the power of the
principal agent exists in nature completely and perfectly: whereas
the instrumental power has a being that passes from one thing into
another, and is incomplete; just as motion is an imperfect act
passing from agent to patient.

Reply Obj. 1: A spiritual power cannot be in a corporeal subject,
after the manner of a permanent and complete power, as the argument
proves. But there is nothing to hinder an instrumental spiritual
power from being in a body; in so far as a body can be moved by a
particular spiritual substance so as to produce a particular
spiritual effect; thus in the very voice which is perceived by the
senses there is a certain spiritual power, inasmuch as it proceeds
from a mental concept, of arousing the mind of the hearer. It is in
this way that a spiritual power is in the sacraments, inasmuch as
they are ordained by God unto the production of a spiritual effect.

Reply Obj. 2: Just as motion, through being an imperfect act, is not
properly in a genus, but is reducible to a genus of perfect act, for