By the same token, when I feel a pain in the foot, physics teaches me that this sensation is produced by means of the nerves dispersed through the foot, which, since they extend upwards like strings as far as the brain, when plucked in the foot also pluck the inmost parts of the brain in which they terminate, thus stimulating a particular motion in these parts of the brain, which is so ordained by nature that it affects the mind with a feeling of pain apparently located in the foot.