Lingering too long in front of the mirror while on several grams of mushrooms began one of the most intense, frightening, and insightful trips I've had. The part of me that says "I," which speaks to you now, was pushed to the back of my consciousness, able only to observe, while three distinct personalities took over my body. Over the course of three to four hours these personalities conversed and contended with one another. Afterward I would come to think of these personalities as "the child," "the demon," and "the adult." I came away from this experience a changed person.
It seems to me immensely unlikely that mind is a mere by-product of matter. For if my mental processes are determined wholly by the motions of atoms in my brain I have no reason to suppose that my beliefs are true. They may be sound chemically, but that does not make them sound logically. And hence I have no reason for supposing my brain to be composed of atoms.
--JBS Haldane