The Pneumatics

-ing. For indeed, if anyone pours water into a vessel which seems empty, as much water as enters the vessel, just as much air will go out. Anyone can understand what has been said from the following. For if one should press down a vessel, which seems empty, inverted into water, and keep it upright, water will not enter into it, even though it be entirely submerged. Therefore it is clear that air, since it is a body, does not permit the water to enter, because the whole space within the vessel is filled with it. If, therefore, one should pierce the bottom of the vessel, water indeed will enter into it through the mouth; but air will go out through the hole. Again, before the bottom is pierced, if one should lift the upright vessel out of the water and turn it over, he will see its entire interior surface to be free from moisture and clean, just as it was before it was submerged. Wherefore air must be considered to be a body. But spirit is produced when it is moved. For spirit is nothing other than air in motion. And so, when the vessel is pierced at the bottom and water is entering, if one should place his hand against the hole, he will feel