The Pneumatics

...the spirit coming out from the vessel. Now this is nothing else than air expelled by the water. One must not therefore suppose that in those things which exist, a certain nature of a vacuum exists collected together by itself, but rather that it is disseminated in small parts throughout the air, the liquid, and other bodies, unless perhaps someone believes that the diamond alone is devoid of the nature of a vacuum, inasmuch as it can neither be fired nor broken, and when struck it passes whole into anvils and hammers. This happens to it, however, not because it lacks a vacuum, but on account of its continuous density. For since the corpuscles of fire are thicker than the vacuum which is in the stone, they by no means enter, but touch only the exterior surface. Wherefore, since they do not penetrate within, neither do they induce heat in it as in other bodies. But the bodies of air indeed cohere among themselves, yet not on every side, but they have certain vacuum intervals interspersed between them, like the sand which is on the shores. And so it must be conceived in the mind that the particles of sand are similar to the bodies of air, while the air, which