Since we have undertaken to make a diligent search into Nature, I cannot but conclude it necessary to declare what Nature is. It is very absurd to attempt a discourse of the essence of natural things, and not to understand what is the power and sphere of Nature. If Aristotle be credited, Nature is the principle of motion and rest, in that thing in which it exists as a principle and not by accident. For all things that are conspicuous to our eyes, which are neither fortuitous nor necessary, nor have a divine original, nor acknowledge any such like cause, are called natural and enjoy their proper nature. Of this sort are earth, fire, water, air, plants, animals; to these may be added all things produced from them, such as showers, hail, thunders, hurricanes, and winds. All these confess they had a beginning, none of these were from eternity, but had something as the origin of them; and likewise animals and plants have a principle whence they are produced. But Nature, which in all these things hath the priority, is not only the principle of motion but of repose; whatsoever enjoys the principle of motion, the same has a possibility to find a dissolution. Therefore on this account it is that Nature is the principle of motion and rest.