And first, if I would now deal rigidly with my Adversary, I might here make a great Question of the very way of Probation which he and others employ, without the least scruple, to evince, that the Bodies commonly call'd mixt, are made up of Earth, Air, Water, and Fire, which they are pleas'd also to call Elements; namely that upon the suppos'd _Analysis_ made by the fire, of the former sort of _Concretes_, there are wont to emerge Bodies resembling those which they take for the Elements. For not to Anticipate here what I foresee I shall have occasion to insist on, when I come to discourse with _Philoponus_ concerning the right that fire has to pass for the proper and Universal Instrument of Analysing mixt Bodies, not to Anticipate that, I say, if I were dispos'd to wrangle, I might alledge, that by _Themistius_ his Experiment it would appear rather that those he calls Elements, are made of those he calls mixt Bodies, then mix'd Bodies of the Elements. For in _Themistius's_ Analyz'd Wood, and in other Bodies dissipated and alter'd by the fire, it appears, and he confesses, that which he takes for Elementary Fire and Water, are made out of the Concrete; but it appears not that the Concrete was made up of Fire and Water. Nor has either He, or any Man, for ought I know, of his perswasion, yet prov'd that nothing can be obtained from a Body by the fire that was not _Pre-existent_ in it. At this unexpected objection, not only _Themistius_, but the rest of the company appear'd not a little surpriz'd; but after a while _Philoponus_ conceiving his opinion, as well as that of _Aristotle_, concern'd in that Objection, You cannot sure (sayes he to _Carneades_) propose this Difficulty; not to call it Cavill, otherwise then as an Exercise of wit, and not as laying any weight upon it. For how can that be separated from a thing that was not existent in it. When, for instance, a Refiner mingles Gold and Lead, and exposing this Mixture upon a Cuppell to the violence of the fire, thereby separates it into pure and refulgent Gold and Lead (which driven off together with the Dross of the Gold is thence call'd _Lithargyrium Auri_) can any man doubt that sees these two so differing substances separated from the Mass, that they were existent in it before it was committed to the fire.