ntelligence
displays its brightest rays. Yet he is not furnished with reason. And
why not? Because he has no experience. Reason, therefore, is an acquired
power, whose light is borrowed from experience or tradition.

Reason is proportional to the experience acquired. Practical reason or
rationality is the ration or portion of experience allotted to each
person.

Reason is to the mental vision exactly what the eye is to optical
vision, and just as the eye borrows its visual action from external
light, so reason borrows its power of clear and correct vision from
traditional experience. The similarity is absolute.

Suppress light, and vision ceases to be possible. Suppress revelation
from intellectual objects, and reason is thenceforth blind.

Between reason and intelligence, although there be inclusion and
co-essentiality in these terms, there is a great difference in the mode
of cognizance; for, as St. Augustine says, intelligence is shown by
simple perception, and reason by the discursive process. Thus, while
intelligence acts simply, as in knowing an intelligible truth by the
light of its own intuition, reason goes toward its end progressively,
from one thing known to another not yet known.

The latter, as St. Thomas says, implies an imperfection. The former, on
the contrary, beseems a perfect being. It is, therefore, evident, adds
the same profound thinker, that reasoning bears the same relation to
knowledge that motion does to repose, or as acquisition to possession.
The one is of an imperfect nature, and the other of a perfect nature.
Boethius compares the intellect to eternity; reason, to time.

Yet human reason, according to the principle which illuminates it,
offers three degrees of elevation which we will distinguish, for
readier comprehension, by three special terms, namely: first, tradition
or the experience of another; second, personal experience; third, the
reason of things.

Trained by tradition, reason is called _common sense_. Trained by
personal experience to the knowledge of principles, reason is called
_science_. Trained by the contemplation of principles to the perfection
of the intellect, reason is called _wisdom_.

What we call practical reason is based upon the authority of tradition
and the lessons of other people's experience in regard to the customary
and moral matters of life.

Speculative or discursive reason judges by the criterion of its own
experience; thereby inferring consequen