e perceive by our senses that the consecrated
hosts become putrefied and corrupted.

_I answer that,_ Corruption is "movement from being into non-being"
(Aristotle, _Phys._ v). Now it has been stated (A. 3) that the
sacramental species retain the same being as they had before when the
substance of the bread was present. Consequently, as the being of
those accidents could be corrupted while the substance of the bread
and wine was present, so likewise they can be corrupted now that the
substance has passed away.

But such accidents could have been previously corrupted in two ways:
in one way, of themselves; in another way, accidentally. They could
be corrupted of themselves, as by alteration of the qualities, and
increase or decrease of the quantity, not in the way in which
increase or decrease is found only in animated bodies, such as the
substances of the bread and wine are not, but by addition or
division; for, as is said in _Metaph._ iii, one dimension is
dissolved by division, and two dimensions result; while on the
contrary, by addition, two dimensions become one. And in this way
such accidents can be corrupted manifestly after consecration,
because the dimensive quantity which remains can receive division and
addition; and since it is the subject of sensible qualities, as
stated above (A. 1), it can likewise be the subject of their
alteration, for instance, if the color or the savor of the bread or
wine be altered.

An accident can be corrupted in another way, through the corruption
of its subject, and in this way also they can be corrupted after
consecration; for although the subject does not remain, still the
being which they had in the subject does remain, which being is
proper, and suited to the subject. And therefore such being can be
corrupted by a contrary agent, as the substance of the bread or wine
was subject to corruption, and, moreover, was not corrupted except by
a preceding alteration regarding the accidents.

Nevertheless, a distinction must be made between each of the aforesaid
corruptions; because, when the body and the blood of Christ succeed in
this sacrament to the substance of the bread and wine, if there be
such change on the part of the accidents as would not have sufficed
for the corruption of the bread and wine, then the body and blood of
Christ do not cease to be under this sacrament on account of such
change, whether the change be on the part of the quality, as for
instance, when th