ly Obj. 1: The sacramental species, although they are forms
existing without matter, still retain the same being which they had
before in matter, and therefore as to their being they are like forms
which are in matter.

Reply Obj. 2: The action of an accidental form depends upon the
action of a substantial form in the same way as the being of accident
depends upon the being of substance; and therefore, as it is an
effect of Divine power that the sacramental species exist without
substance, so is it an effect of Divine power that they can act
without a substantial form, because every action of a substantial or
accidental form depends upon God as the first agent.

Reply Obj. 3: The change which terminates in a substantial form is
not effected by a substantial form directly, but by means of the
active and passive qualities, which act in virtue of the substantial
form. But by Divine power this instrumental energy is retained in the
sacramental species, just as it was before: and consequently their
action can be directed to a substantial form instrumentally, just in
the same way as anything can act outside its species, not as by its
own power, but by the power of the chief agent.
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FOURTH ARTICLE [III, Q. 77, Art. 4]

Whether the Sacramental Species Can Be Corrupted?

Objection 1: It seems that the sacramental species cannot be
corrupted, because corruption comes of the separation of the form
from the matter. But the matter of the bread does not remain in this
sacrament, as is clear from what was said above (Q. 75, A. 2).
Therefore these species cannot be corrupted.

Obj. 2: Further, no form is corrupted except accidentally, that is,
when its subject is corrupted; hence self-subsisting forms are
incorruptible, as is seen in spiritual substances. But the
sacramental species are forms without a subject. Therefore they
cannot be corrupted.

Obj. 3: Further, if they be corrupted, it will either be naturally or
miraculously. But they cannot be corrupted naturally, because no
subject of corruption can be assigned as remaining after the
corruption has taken place. Neither can they be corrupted
miraculously, because the miracles which occur in this sacrament take
place in virtue of the consecration, whereby the sacramental species
are preserved: and the same thing is not the cause of preservation
and of corruption. Therefore, in no way can the sacramental species
be corrupted.

_On the contrary,_ W