e observed in reference to
knowledge. In the first place, knowledge itself, which, if it be of
the past, is called _memory,_ if of the present, whether contingent
or necessary, is called _understanding_ or _intelligence._ Secondly,
the acquiring of knowledge, which is caused either by teaching, to
which pertains _docility,_ or by _discovery,_ and to this belongs to
_eustochia_, i.e. "a happy conjecture," of which _shrewdness_ is a
part, which is a "quick conjecture of the middle term," as stated in
Poster. i, 9. Thirdly, the use of knowledge, in as much as we proceed
from things known to knowledge or judgment of other things, and this
belongs to _reasoning._ And the reason, in order to command aright,
requires to have three conditions. First, to order that which is
befitting the end, and this belongs to _foresight;_ secondly, to
attend to the circumstances of the matter in hand, and this belongs
to _circumspection;_ thirdly, to avoid obstacles, and this belongs to
_caution._

The subjective parts of a virtue are its various species. In this way
the parts of prudence, if we take them properly, are the prudence
whereby a man rules himself, and the prudence whereby a man governs a
multitude, which differ specifically as stated above (Q. 47, A. 11).
Again, the prudence whereby a multitude is governed, is divided into
various species according to the various kinds of multitude. There is
the multitude which is united together for some particular purpose;
thus an army is gathered together to fight, and the prudence that
governs this is called _military._ There is also the multitude that
is united together for the whole of life; such is the multitude of a
home or family, and this is ruled by _domestic prudence_: and such
again is the multitude of a city or kingdom, the ruling principle of
which is _regnative prudence_ in the ruler, and _political prudence,_
simply so called, in the subjects.

If, however, prudence be taken in a wide sense, as including also
speculative knowledge, as stated above (Q. 47, A. 2, ad 2) then its
parts include _dialectics,_ _rhetoric_ and _physics,_ according to
three methods of prudence in the sciences. The first of these is the
attaining of science by demonstration, which belongs to _physics_ (if
physics be understood to comprise all demonstrative sciences). The
second method is to arrive at an opinion through probable premises,
and this belongs to _dialectics._ The third method is to employ
con