"The action of the consciousness-expanding drug gives the person access to hitherto inaccessible psychic material, facilitates thinking and feeling in unfamiliar ways, allows perception of himself and the world about him in an unhabitual manner, and makes it possible for him to reexamine his basic beliefs and values in the light of such new data...Use of the psychedelic agents offers some confirmation to the testimony of mystics that there are dimensions of human experience which lie beyond ordinary consciousness, yet which can be consciously tapped. Science has hitherto failed to recognize such experience, yet without its inclusion no science of man can pretend to represent him in his more creative, more human aspects. If these dimensions cannot be studied by our present scientific methodology, we had best attempt to find new ways by which they can." W.W. Harman

http://www.hofmann.org/papers/IssueCED.htm