Amongst the senses, the deity has in us lit sight to view the objects in the heavens, and for the reception of knowledge; while to make us capable to receive speech and melody, he has in us implanted hearing, of which he who is deprived thereof from birth will become dumb, nor be able to utter any speech, and that is why this sense is said to be related closest to speech. .As many affections of the body as have a name are so called with reference to touch; and others from relation to their seat. Touch judges of the properties connected with life, such as warmth, coldness, dryness, moisture, smoothness, roughness, and of things, that they are yielding, opposing, hard, or soft. Touch also decides of heaviness or lightness. Reason defines these affections as being centripetal and centrifugal; which men mean to express when they say below, and middle. For the centre of a sphere is below, and that part lying above it and stretching to the circumference, is called upwardness.
Now what is warm appears to consist of fine particles, causing bodies to separate; while coldness consists of the grossness of the particles, causing a tendency to condense.
The circumstances connected with the sense of taste are similar to those of touch. For substances grow either smooth or rough by concretion and secretion, by entering the pores, and assuming shapes. For those that cause the tongue to melt away, or that scrape it, appear to be rough; while those that act moderately in scraping appear brackish; while those that inflame or separate the skin are acrid; while their opposites, the smooth sweet, are reduced to a juicy state.
Of smelling, the kinds have not been defined; for, because of their percolating through narrow pores, that are too stiff to be closed or separated, things seem to be sweet-smelling or bad-smelling from the putrefaction or concoction of the earth and similar substances.
A vocal sound is a percussion in the air, arriving at the soul through the ears; the pores (or communications) of which reach to the liver; and among them is breath, by the movement of which hearing exists. Now of the voice and hearing, that portion which is quick is acute; while that which is slow, is grave; the medium being the most harmonious. What is much and diffused, is great; what is little and compressed, is small; what is arranged according to musical proportions is in tune, while that which is unarranged, and unproportionate, is out of tune, and not properly adjusted.
The fourth kind of things relating to the senses is the most multiform and various, and they are called objects of sight, in which are all kinds of colors, and an infinity of colored substances. The principle are four: white, black, brilliant (blue) and red, out of a mixture of which all other colors are prepared. What is white causes the vision to expand, and what is black causes it to contract; just as warmth expands, and cold contracts, and what is rough contracts the tasting, and what is sharp dilates it.