13. For two principles of nature were now come to their birth and luxuriance, namely, active and passive principles, the former of which filled the whole universe, for ether was the atmosphere of such principles or forces; but the latter, or passive principles, were heaped together into one, and constituted globes suspended and equally balanced in the centres of the circumgyration of the active forces.
(The origin of the air from the active principles, of those of the ether, and from passive principles, or those of the earth.)
[2] But these principles were to be joined together, and one was to be given to the other in a kind of marriage, in order that a new and mediating atmosphere might be conceived, which might proximately encompass the orb, and receive the solar fires, and temper them according to the variation of its state, or density and column; when this atmosphere was born it was called air, deriving from its birth this [property], that in all modes of acting it emulates ether, and, moreover, being heavy, presses itself and thereby the earth. 1
Mga talababa:
1. Air when modified produces sound, as ether produces light; the organ of hearing is allotted to the former, but that of seeing to the latter.
(The agreement of the nature of the air with the ether.)
That air emulates ether in its modes is evident from its sound, which is propagated by right lines to a considerable distance, like light, and conveyed in every direction from the different centres of motion; also that each in like manner rebounds or is reflected according to the angle of incidence, and presses equally inwards and outwards in the manner of a perpetual circle or sphere. But that air is at the same time a concrete of passive principles, or principles endowed with a vu inertia, is evident from its manifest gravity, wherein it differs from ether, which, in consequence of its purely active force, whence comes its elasticity, derives this [property], that it is neither light nor heavy.
