One gains knowledge in four ways: (1) by accepting it on authority of someone else, (2) by thinking, (3) by experiencing, (4) and by feeling which may be called intuition, mysticism, inspiration, or revelation.*

In philosophical language, the classis ways of approaching reality are authority, rationalism, empiricism, and mysticism.

-Lowell L. Bennion, Religion and the Pursuit of Truth (pg. 24)