ity.

_On the contrary,_ Augustine says (Soliloq. ii, 6), "It appears that the
senses entrap us into error by their deceptive similitudes."

_I answer that,_ Falsity is not to be sought in the senses except as
truth is in them. Now truth is not in them in such a way as that the
senses know truth, but in so far as they apprehend sensible things
truly, as said above (Q. 16, A. 2), and this takes place through
the senses apprehending things as they are, and hence it happens that
falsity exists in the senses through their apprehending or judging
things to be otherwise than they really are.

The knowledge of things by the senses is in proportion to the
existence of their likeness in the senses; and the likeness of a thing
can exist in the senses in three ways. In the first way, primarily and
of its own nature, as in sight there is the likeness of colors, and of
other sensible objects proper to it. Secondly, of its own nature,
though not primarily; as in sight there is the likeness of shape,
size, and of other sensible objects common to more than one sense.
Thirdly, neither primarily nor of its own nature, but accidentally, as
in sight, there is the likeness of a man, not as man, but in so far as
it is accidental to the colored object to be a man.

Sense, then, has no false knowledge about its proper objects, except
accidentally and rarely, and then, because of the unsound organ it
does not receive the sensible form rightly; just as other passive
subjects because of their indisposition receive defectively the
impressions of the agent. Hence, for instance, it happens that on
account of an unhealthy tongue sweet seems bitter to a sick person.
But as to common objects of sense, and accidental objects, even a
rightly disposed sense may have a false judgment, because it is
referred to them not directly, but accidentally, or as a consequence
of being directed to other things.

Reply Obj. 1: The affection of sense is its sensation itself. Hence,
from the fact that sense reports as it is affected, it follows that
we are not deceived in the judgment by which we judge that we
experience sensation. Since, however, sense is sometimes affected
erroneously of that object, it follows that it sometimes reports
erroneously of that object; and thus we are deceived by sense about
the object, but not about the fact of sensation.

Reply Obj. 2: Falsity is said not to be proper to sense, since sense
is not deceived as to its proper object.