Reason is one of the two sides of the mind, the other being intelligence. Reason is doubly subject to the object it observes and to the logic that sets the rules for its calculations and reasoning. Reason is to the conceptible what intelligence is to the intelligible – far more vast, if not unlimited. The conceptible is an abstraction and a construction (concepts are generated and developed), the intelligible is a reception (a mirror, speculum in Latin) of signifiance. Reason operates in the hypothetico-deductive to develop knowledge and maintains the distance between subject and object; intelligence is the faculty of noesis, knowledge by participation, identification of the known, the knowing and knowledge.

See the paper Reason and Intelligence, the Two Sides of the Mind.