The Pneumatics

...to write, we have resolved as has been said. For indeed, by the union of air, fire, water, and earth—and by the coming together of three elements, or even four, with one another—various arrangements are produced; some indeed providing for the necessary uses of our life, others truly exciting a certain awesome wonder.

But before we proceed to those things which are to be said, we must treat of the vacuum. For some affirm that universally there is no vacuum at all; others, that there is no continuous vacuum in nature, but that it is distributed in small particles through air, liquid, fire, and other bodies; with whom it is most fitting to agree. For from those things which are manifest and fall under the senses, it will be demonstrated in what follows that this is so. For vessels, which to many seem empty, are not empty as they suppose, but are full of air. Now air, as is the opinion of those who treat of nature, consists of small and light bodies, for the most part not appear-