3471. The cause is hence manifest why the learned do not believe in a life after death, nor in spirit, viz., that they abstract thought from its organic [relations], just as they would sight and hearing from their organs. To this we may add, that if spirit was nothing but thought, man would have no need of so much brain as he has, for the whole brain is an organ of the internal senses. Indeed the skull might in that case be wholly emptied of its contents, and still the thought act as spirit. How then can it fail to appear to the learned of the world, that there are organics of thought in the brain, from whence flow invisible fibers, along which the thoughts pass from the [outward] senses to the [interior] organics, and from the organics to the muscular activities?