As for changes that go beyond the limits of nature, they occur either as a result of certain transformations in the very substance of the air, or as a result of transformations that take place in its qualities. As for the transformations taking place in matter, they consist in the fact that the substance of the air changes and becomes bad, since one of its qualities has increased excessively or, conversely, decreased. This is called “plague,” that is, some decay that occurs in the air and is similar to the decay of stagnant, spoiled water.
By “air” we do not mean a simple, naked element, for this is not the air that surrounds us. If it exists in its pure form, then other air probably exists. After all, every simple, naked element does not rot; it either undergoes a transformation in its quality, or is transformed by its very substance into another simple element, when, for example, water turns into air. No, we mean by air a body dispersed in space, that is, a substance mixed from true air, from particles of water vapor and from particles of earth rising upward in smoke and dust, as well as from fiery particles.
We say that this is air, just as we say “water” about sea water and swamp water, although this is not pure simple water, but water mixed with air, earth and fire, but only water predominates in it. Such air can rot and its substance turns into something bad, just as swamp water rots and its substance becomes bad. Most often, “plague” and air decay occur in late summer and autumn; We will mention the manifestations accompanying the “craze” elsewhere.
As for the transformations of air qualities, they consist in the fact that the air, due to its heat or cold, turns into an intolerable quality and because of this, crops and the offspring of animals deteriorate. This happens either due to a change in what is essentially homogeneous, as, for example, during scorching heat, when it becomes harmful, or due to the transformation of the opposite in essence, as, for example, during severe cold in summer due to some circumstance.
When the air changes, various phenomena occur in the body because of this. By rotting, the air makes the juices rotten and, first of all, the juice contained in the heart rots, since it is easier for it to reach this juice than other juices. If the air is very hot, it relaxes the joints and dissolves the internal moisture, increasing thirst, and also dissolves the pneuma, causing a loss of strength, and interferes with digestion, dissipating the internal innate warmth, which is an instrument of nature.
Hot air makes the complexion yellow, dissolving the bloody juices that give the face a blush, and, giving bile a predominance over other juices, warms the heart with an unnatural heat, rots and causes the juices to flow, directing them into cavities and weak organs. Such air is by no means good for a body in a healthy state, but is sometimes useful for dropsy, paralysis, and those suffering from cold case, cold catarrh, wet spasms, and wet facial paralysis.
As for cold air, such air locks the innate warmth inside; if it does not become so cold that it penetrates inside the body, then it is fatal. Not too cold air prevents the flow of bad juices and locks them up, but it causes catarrhs, weakens the nerves and causes great harm to the pulmonary tube and lungs. If it is not very excessive in coldness, it strengthens digestion, strengthens all the internal functions of the body and stimulates the appetite. Such air is generally more beneficial for healthy people than excessively hot air, and its harmfulness affects the functions associated with the nerves, and also consists in the fact that it clogs the pores and compresses the contents in the spaces between the bones.
Humidified air is beneficial and suitable for most natures. It improves the complexion and skin and softens it, cleanses the pores so that they open, but predisposes the juices to putrefaction. Dry air does the opposite.