There are many sorts of _Airs_, as there is of other Creatures, of one and the same kind: but, for Elemental Air, is composed of very Rare, Figurative Motions; and the Innate Motions, I conceive to be somewhat of the Nature of Water, viz. Circular Figurative Motions, only of a more Dilating Property; which causes Air, not to be Wet, but extraordinary Rare; which again causes it to be somewhat of the nature of Light: for, the Rarity occasions Air to be very searching and penetrating; also, dividable and compoundable: but, the Rarity of Air, is the cause that it is not subject to some sorts of Human Perception; but yet, not so Rare, as not to be subject to Human Respirations; which is one sort of Human Perception: for, all Parts of all Creatures, are perceptive one way, or another: but, as I said, there are many sorts of Air; as, some Cold, some Hot; some Dry, some Moist; some Sharp; some Corrupt, some Pure, some Gross; and numbers more: but, many of these sorts are rather Metamorphosed Vapours, and Waters, than pure Elemental Air: for, the pure Elemental Air, is, in my opinion, more searching and penetrating, than Light; by reason Light may be more easily eclipsed, or stopt; when as Air will search every Pore, and every Creature, to get entrance. CHAP. VI. Of the Innate Figurative Motion of Fire. The Innate Figurative Motions of Elemental Fire, seem the most difficult to Human Perception, and Conception: for, by the Agilness, it seems to be more pure than the other sorts of Elements; yet, by the Light, or Visibleness, it seems more gross than Air; but, by the dilating Property, it seems to be more rare than air, at least, as rare as Air. By the Glassie or Shining Property, it seems to be of Smooth and Even Parts: also, by the piercing and wounding Property, Fire seems to be composed of sharp-pointed Figurative Motions: Wherefore, the Innate Figurative Motions of Fire, are, Pure, Rare, Smooth, Sharp Points, which can move in Circles, Squares, Triangles, Parallels, or any other sorts of Exterior Figures, without an alteration of its Interior Nature; as may be observed by many sorts of Fuels: as also, it can contract and dilate its Parts, without any alteration of its Innate Property. CHAP. VII. Of the Productions of Elemental Fire.