Mysticism: 1) The doctrine or belief that direct knowledge of God, of spiritual truth, etc., is attainable . . . in a way differing from ordinary sense perception or the use of logical reasoning. 2) Any type of theory asserting the possibility of attaining knowledge or power through faith or spiritual insight. 3) Hence, vague speculation.
Webster neatly summarizes the conventional, science-minded attitude: an approach to truth that bypasses "ordinary sense perception" adds up to nothing but "vague speculation." Yet mystics—the experimentalists of religion—may not seem so unscientific to a mid-20th century psychiatrist....