Bad Advertisement? Are you a Christian? Online Store: | PREVIOUS SECTION - NEXT SECTION - HELP Chapter XVIII.—Concerning Sensation. Sensation is that faculty of the soul whereby material objects can be apprehended or discriminated. And the sensoria are the organs or members through which sensations are conveyed. And the objects of sense are the things that come within the province of sensation. And lastly, the subject of sense is the living animal which possesses the faculty of sensation. Now there are five senses, and likewise five organs of sense. The first sense is sight: and the sensoria or organs of sight are the nerves of the brain and the eyes. Now sight is primarily perception of colour, but along with the colour it discriminates the body that has colour, and its size and form, and locality, and the intervening space and the number1834
The second sense is hearing, whereby voices and sounds are perceived. And it distinguishes these as sharp or deep, or smooth or loud. Its organs are the soft nerves of the brain, and the structure of the ears. Further, man and the ape are the only animals that do not move their ears. The third sense is smell, which is caused by the nostrils transmitting the vapours to the brain: and it is bounded by the extreme limits of the anterior ventricle of the brain. It is the faculty by which vapours are perceived and apprehended. Now, the most generic distinction between vapours is whether they have a good or an evil odour, or form an intermediate class with neither a good nor an evil odour. A good odour is produced by the thorough digestion in the body of the humours. When they are only moderately digested the intermediate class is formed, and when the digestion is very imperfect or utterly wanting, an evil odour results. The fourth sense is taste: it is the faculty whereby the humours are apprehended or perceived, and its organs of sense are the tongue, and more especially the lips, and the palate (which the Greeks call οὐρανίσκος ), and in these are nerves that come from the brain and are spread out, and convey to the dominant part of the soul the perception or sensation they have encountered1835
The fifth sense is touch, which is common to all living things1836
The Creator, it is to be noted, fashioned all the other organs of sense in pairs, so that if one were destroyed, the other might fill its place. For there are two eyes, two ears, two orifices of the nose, and two tongues, which in some animals, such as snakes, are separate, but in others, like man, are united. But touch is spread over the whole body with the exception of bones, nerves, nails, horns, hairs, ligaments, and other such structures. Further, it is to be observed that sight is possible only in straight lines, whereas smell and hearing are not limited to straight lines only, but act in all directions. Touch, again, and taste act neither in straight lines, nor in every direction, but only when each comes near to the sensible objects that are proper to it.
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