I answer, The cause of that may be, that the Figurative Motions of _Amber_, may sympathize with the Exterior consistent Motions of the Fly, which may cause the Exterior Shape of the Flye to continue, although the Innate Nature be altered. But Air is, as all other Creatures are, both Beneficial, and Hurtful to each other; for Nature is poysed with Opposites: for we may perceive, that several Creatures are both Beneficial and Hurtful to each other: as for example, A Bear kills a Man; and, on the other side, a Bear's Skin will cure a Man of some Disease. Also, a _Wild-Boar_ will kill a Man; and the _Boar_'s Flesh will nourish a Man. Fire will burn a Man, and preserve a Man; and Millions of such Examples may be proposed. The same may be said of Air, which may occasion Good or Evil to other Creatures; as, the _Amber_ may occasion the death of a Fly; and, on the other side, may occasion the Preservation, or Continuation of the Fly's Exterior Figure, or Form: but, Nature being without _Vacuum_, all her Parts must be be joined; and her Actions being poysed, there must be both Sympathetical, and Antipathetical actions, amongst all Creatures. The Thirteenth Part. CHAP. I. Of the Innate Figurative Motions of Metals. All sorts of _Metals_, in my opinion, are of some sorts of Circular Motions; but not like that sort, that is Water: for, the Water-Circle doth extend outward, from the Center; whereas, in my opinion, the Circular Motion of Metal, draws inward, from the Circumference. Also, in my opinion, the Circular Motions are dense, flat, edged, even, and smooth; for, all Bright and Glassie Bodies are smooth: and, though Edges are wounding Figures; yet, Edges are rather of the Nature of a Line, than of a Point. Again, all Motions that tend to a Center, are more fixt than those that extend to a Circumference: but, it is according to the degree of their Extensions, that those Creatures are more or less fixt; which is the cause that some sorts of Metals are more fixt than others; and that causes Gold to be the most fixt of all other sorts of Metals; and seems to be too strong for the Effects of Fire. But this is to be noted, That some Metals are more near related to some sort, than other: as for example, There is no Lead, without some Silver; so that Silver seems to be but a well-digested Lead. And certainly, Copper hath some near relation to Gold, although not so near related, as Lead is to Silver. CHAP. II. Of the Melting of Metals.