I believe that man originated his first ideas of the supernatural from the external phenomena of nature which were perceptible to one or more of his five senses; his first theogony was a natural one and one taken directly from nature. In ideation the primal bases of thought must have been founded, ab initio, upon sensual perceptions; hence, must have been materialistic and natural. Spencer, on the contrary, maintains that in man, "the first traceable conception of a supernatural being is the conception of a ghost."