2. I. SENSATION OR THE PASSION OF THE BODY
That sensations are external and internal. The external senses are touch, taste, smell, hearing, and sight; these are also called the bodily senses. Internal sensation is spoken of as the perception or apperception of the things that flow in from the organs of the external senses. Inmost sensation is intellection; for the things which are sensated and perceived must also be rationally understood. But the inmost of all, or the principle of sensations, belongs to the soul and is called pure intellection or intelligence; for our ability to sensate, perceive, understand, belongs to the soul alone. Just as sensations are external and internal, so also are the organs of sensations. The organ of touch is the external surface of the whole body; the organ of taste is the tongue; [the organ] of smell is the membrane of the nostrils and their cavities; the organ of hearing is the ear, and of sight the eye. The organ of perception is the cortical cerebrum, or the cortical substance of the cerebrum. The organ of intellection or of inmost sensation is the purest cortex, or that simple cortex which is contained in each cortical gland. These organs, both the internal and the external, are called sensories, the cerebrum being the common sensory of all the external sensories.
That external sensations communicate with internal sensations, or the external sensories with the interior sensories, and with the inmost, by means of fibers. Every one who is imbued with the first rudiments of anatomy knows that external sensations communicate with internal by means of fibers. For, from every point of the cuticle, there issues a fiber which runs toward the medulla spinalis or oblongata, this being the reason why such fibers are called sensory and are distinguished from motory fibers; from every point of the tongue, a fiber of the ninth, eighth, and fifth pair of the head; from the nostrils, fibers run through the cribriform plate into the mammillary processes which are affixed to the anterior surface of the cerebrum like two bottles; from the ear, a fiber of the seventh pair, both hard and soft; and from the eye proceeds the great optic nerve. These fibers run on until they reach their beginnings, that is, the cortical glands. In these beginnings or glands resides all internal sensation, this being dependent on their change of state. From this gland again are extended simple fibers reaching to a purer cortex, which we call the simple cortex, whence comes the intellection of the things apperceived and sensated. Thus by means of fibers there is a continual communication of external and internal sensations. This also is the reason why a sense straightway languishes or dies away, as soon as the intermediary nerve is cut, torn away, or obstructed-as is clearly apparent from the innumerable effects of diseases.
