ccording to Augustine (De Trin. xii, 7) "is
intent on the consideration and consultation of things eternal"; and
that what the Philosopher calls the "reasoning" or "opinionative" part
is the same as the lower reason, which, according to Augustine, "is
intent on the disposal of temporal things." Therefore the higher
reason is another power than the lower.

Obj. 4: Further, Damascene says (De Fide Orth. ii) that "opinion
rises from the imagination: then the mind by judging of the truth or
error of the opinion discovers the truth: whence _mens_ (mind) is
derived from _metiendo_ (measuring). And therefore the intellect
regards those things which are already subject to judgment and true
decision." Therefore the opinionative power, which is the lower
reason, is distinct from the mind and the intellect, by which we may
understand the higher reason.

_On the contrary,_ Augustine says (De Trin. xii, 4) that "the higher
and lower reason are only distinct by their functions." Therefore
they are not two powers.

_I answer that,_ The higher and lower reason, as they are understood
by Augustine, can in no way be two powers of the soul. For he says
that "the higher reason is that which is intent on the contemplation
and consultation of things eternal": forasmuch as in contemplation it
sees them in themselves, and in consultation it takes its rules of
action from them. But he calls the lower reason that which "is intent
on the disposal of temporal things." Now these two--namely, eternal
and temporal--are related to our knowledge in this way, that one of
them is the means of knowing the other. For by way of discovery, we
come through knowledge of temporal things to that of things eternal,
according to the words of the Apostle (Rom. 1:20), "The invisible
things of God are clearly seen, being understood by the things that
are made": while by way of judgment, from eternal things already
known, we judge of temporal things, and according to laws of things
eternal we dispose of temporal things.

But it may happen that the medium and what is attained thereby belong
to different habits: as the first indemonstrable principles belong to
the habit of the intellect; whereas the conclusions which we draw
from them belong to the habit of science. And so it happens that from
the principles of geometry we draw a conclusion in another
science--for example, perspective. But the power of the reason is
such that both medium and term belong to it. For