Socrates was that knowledge can never be overcome by
passion; wherefore he held every virtue to be a kind of knowledge,
and every sin a kind of ignorance. In this he was somewhat right,
because, since the object of the will is a good or an apparent good,
it is never moved to an evil, unless that which is not good appear
good in some respect to the reason; so that the will would never tend
to evil, unless there were ignorance or error in the reason. Hence it
is written (Prov. 14:22): "They err that work evil."

Experience, however, shows that many act contrary to the knowledge
that they have, and this is confirmed by Divine authority, according
to the words of Luke 12:47: "The servant who knew that the will of
his lord . . . and did not . . . shall be beaten with many stripes,"
and of James 4:17: "To him . . . who knoweth to do good, and doth it
not, to him it is a sin." Consequently he was not altogether right,
and it is necessary, with the Philosopher (Ethic. vii, 3) to make a
distinction. Because, since man is directed to right action by a
twofold knowledge, viz. universal and particular, a defect in either
of them suffices to hinder the rectitude of the will and of the deed,
as stated above (Q. 76, A. 1). It may happen, then, that a man has
some knowledge in general, e.g. that no fornication is lawful, and
yet he does not know in particular that this act, which is
fornication, must not be done; and this suffices for the will not to
follow the universal knowledge of the reason. Again, it must be
observed that nothing prevents a thing which is known habitually from
not being considered actually: so that it is possible for a man to
have correct knowledge not only in general but also in particular,
and yet not to consider his knowledge actually: and in such a case it
does not seem difficult for a man to act counter to what he does not
actually consider. Now, that a man sometimes fails to consider in
particular what he knows habitually, may happen through mere lack of
attention: for instance, a man who knows geometry, may not attend to
the consideration of geometrical conclusions, which he is ready to
consider at any moment. Sometimes man fails to consider actually what
he knows habitually, on account of some hindrance supervening, e.g.
some external occupation, or some bodily infirmity; and, in this way,
a man who is in a state of passion, fails to consider in particular
what he knows in general, in so far as the passion