Elements are some simple bodies. These are the primary particles of the human body and other things, incapable of dividing into parts of different shapes, i.e., such particles into which complex bodies are divided. From the mixture of elements, different forms of existing things arise.
The doctor must take on faith the words of the naturalist that there are only four elements, no more. Two of them are light, two are heavy light ones are fire and air, heavy ones are water and earth. The earth is a simple body, the natural place of which is the middle of all things by nature it rests in this place and by nature it moves towards it if it is at a distance from it this is the absolute heaviness of the earth.
The earth is cold and dry by its nature, in other words, in the nature of the earth, when it remains on its own with what conditions it, and is not changed by anything outside, tangible cold and dryness appear. The presence of earth in existing things contributes to cohesion and strength, preserving outlines and shapes.
As for water, it is a simple body, which in its natural place surrounds the earth and is surrounded by air, when air and water are in their natural state this is the relative gravity of water. The water is cold and wet in other words, in the nature of water, when it remains by itself with that which determines it, and is not opposed by anything from the outside, tangible coldness and a state called humidity appear. Humidity means that the nature of water contains the ability to disintegrate at the slightest cause. the smallest particles up to complete separation, as well as combine and take any form, (6) without retaining it in the future. Water is found in everything that exists, so that the forms are soft, the parts of which it is desirable to give a certain figure, outline and proportionality. The fact is that everything wet easily loses the shape of any figure, it just as easily takes it, just as dry, although it has difficulty taking the shape of any figure, also loses it with difficulty.
Whenever dry is mixed with wet, it acquires from the moisture the ability to easily stretch and take on certain shapes, and the wet acquires from dry the ability to firmly maintain the strength and proportionality that has arisen in it. Thanks to the wet, the dry is united and does not crumble, and the wet, thanks to the dry, is held back and does not spread.
As for air, it is a simple body, the natural place of which is above water and below fire this is its relative ease. The nature of air is hot and humid, similar to what we said before. Air is found in existing things so that they are loose, rarefied, light and disjointed.
Fire is a simple body whose natural place is above all other elements. The natural location of fire is the concave surface of the celestial sphere, at which formation and destruction end. This is its absolute lightness. The nature of fire is hot and dry. It is in existing things so that they ripen, become rarer and mix. Fire flows in things, conducting airy substance through them, so that the property of pure coldness of both heavy elements is broken and they pass from the state of elementaryness to the state of mixture.
Two heavy elements are more useful for the existence of organs and their rest and two lungs are more useful for the existence of air and their movement, as well as for setting organs in motion, although the first mover is the soul. That's all the elements.