CHAPTER X.

THE KNOWABLE AND UNKNOWABLE—BRAIN AND THOUGHT.

Basis of knowledge—Perception—Constitution of brain—White and grey matter—Average size and weight of brains—European, negro, and ape—Mechanism of perception—Sensory and motor nerves—Separate areas of brain—Sensory and motor centres—Abnormal states of brain—Hypnotism—Somnambulism—Trance—Thought-reading— Spiritualism—Reflex action—Ideas how formed—Number and space—Creation unknowable—Conceptions based on perceptions—Metaphysics—Descartes, Kant, Berkeley—Anthropomorphism—Laws of nature 125