ment, that air lofeth in the lungs the power of feeding flame. Hence it is concluded, that the fame thing in air contributes both to life and flame. Vital flame furvives culinary flame in vacuo: therefore it requires lefs of that thing to sustain it.

202. What this may be, whether fome certain proportion, or fome peculiar parts of æther, is not eafy to fay. But thus much feems plain, that whatever is afcribed to acid may be also ascribed. to fire or æther. The particles of æther fly afunder with the greatest force: therefore, agreeably to Sir Ifaac Newton's doctrine, when united they must attract each other with the greatest force. Therefore they conftitute the acid. For whatsoever.

ftrongly attracts and is attracted, may be called an acid, as Sir Ifaac Newton informs us in his tract De acido. Hence it should feem, that the fulphur of Homberg, and the acid of Sir Ifaac are at bot-. tom one and the fame thing, to wit, pure fire or æther.

203. The vital flame or ethereal fpirit, being attracted and imprisoned in groffer bodies, feemeth to be fet free and carried off, by the fuperior attraction of a fubtil and pure flame. Hence, perhaps it is, that lightening kills animals, and turns, fpirituous liquors vapid in an inftant.

204. Hippocrates in his book concerning the Heart obferveth, that the foul of man is not nourished by meats and drinks from the lower belly, but by a pure and luminous fubftance darting its. rays, and diftributing a non-natural nourishment, as he terms it, in like manner as that from the intestines is distributed to all parts of the body. This luminous non-natural nourishment, though it be fecreted from the blood, is exprefly faid not to come from the lower belly. It is plain, therefore,

he

he thought it came into the blood either by refpiration, or by attraction through the pores. And it must be acknowledged, that fomewhat igneous or æthereal brought by the air into the blood feems to nourish, though not the foul itfelf, yet the interior tunicle of the foul, the auraï fimplicis ignem.

205. That there is really fuch a thing as vital flame, actually kindled, nourish'd, and extinguish'd like common flame, and by the fame means, is an opinion of fome moderns, particularly of Doctor Willis in his tract De fanguinis accenfione: that it requires conftant eventilation, through the trachea and pores of the body, for the discharge of a fuliginous and excrementitious vapour : and that this vital flame, being extremely fubtil, might not be feen any more than fhining flies or ignes fatui by day-light. And yet it hath fometimes become vifible on divers perfons, of which there are undoubted inftances. This is Dr. Willis's notion: and perhaps there may be fome truth in this, if it be fo understood, as that light or fire might indeed constitute the animal spirit or immediate vehicle of the foul.

206. There have not been wanting thofe, who, not content to suppose light the most pure and refined of all corporeal beings, have gone farther, and bestowed upon it fome attributes of a yet higher nature. Julianus the Platonic philofopher, as cited by Ficinus, faith, it was a doctrine in the theology of the Phoenicians, that there is diffused throughout the univerfe, a pellucid and fhining nature pure and impaffive, the act of a pure intelligence. And Ficinus himfelf undertakes to prove, that light is incorporeal, by feveral arguments: Becaufe it enlightens and fills a great space in an inftant, and without oppofition: Because feveral

F

lights meet without refifting each other: Because light cannot be defiled by filth of any kind: Because the folar light is not fixed in any fubject: Laftly, because it contracts and expands it felf fo eafily without collifion, condenfation, rarefaction, or delay throughout the vastest space. Thefe reafons are given by Ficinus, in his comment on the firft book of the fecond Ennead of Plotinus.

207. But it is now well known, that light moves, that it's motion is not inftantaneous: that it is capable of condensation, rarefaction, and collifion that it can be mixed with other bodies, enter their composition, and increase their weight (a). All which feems fufficiently to overthrow those arguments of Ficinus, and fhew light to be corporeal. There appears indeed fome difficulty at firft fight, about the non-refiftance of rays or particles of light occurring one to another, in all poffible directions or from all points. Particularly, if we fuppofe the hollow furface of a large fphere, ftudded with eyes looking inwards one at another, it may perhaps seem hard to conceive, how distinct rays from every eye should arrive at every other eye without juftling, repelling, and confounding each other.

208. But thefe difficulties may be got over by confidering in the first place, that vifible points are not mathematical points, and confequently, that we are not to fuppofe every point of space a radiating point. Secondly, by granting that many rays do refift and intercept each other, notwithstanding which the act of vifion may be performed. Since as every point of the object is not feen, fo it is not neceffary that rays from every fuch point arrive at the eye. We often fee

(e) 169, 192, 193.

an

an object, though more dimly, when many rays are intercepted by a grofs medium.

209. Befides, we may fuppofe the particles of light to be indefinitely fmall, that is, as fmall as we pleafe, and their aggregate to bear as fmall a proportion to the void as we pleafe, there being nothing in this that contradicts the phænomena. And there needs nothing more in order to conceive the poffibility of rays paffing from and to all visible points, although they be not incorporeal. Suppose a hundred ports placed round a circular fea, and fhips failing from each port to every other; the larger the fea, and the fmaller the veffels are fuppofed, the lefs danger will there be of their striking against each other. But as there is by hypothefis no limited proportion be tween the fea and the fhips, the void and folid particles of light, fo there is no difficulty that can oblige us to conclude the fun's light incorporeal from it's free paffage; efpecially when there are fo many clear proofs of the contrary. As for the difficulty, therefore, attending the fuppofition of a fphere ftudded with eyes looking at each other, this is removed only by fuppofing the particles of light exceeding fmall relatively to the empty spaces.

210. Plotinus fuppofeth, that from the fun's light which is corporeal, there fprings forth another equivocal light which is incorporeal, and as it were the brightnefs of the former. Marfilius Ficinus alfo, obferving it to be a doctrine in the Timæus of Plato, that there is an occult fire or fpirit diffused throughout the univerfe, intimates that this fame occult invifible fire or light is, as it were, the fight of the mundane foul. And Plotinus, in his fourth Ennead, fheweth it to be his opinion, that the world feeth it felf and all it's

parts. The Platonic philofophers do wonderfully refine upon light, and foar very high: from coal to flame; from flame to light; from this vifible light to the occult light of the celeftial or mundane foul, which they fuppofed to pervade and agitate the fubftance of the universe by it's vigorous and expanfive motion.

211. If we may believe Diogenes Laertius, the Pythagoræan philofophers thought there was a certain pure heat or fire, which had fomewhat divine in it, by the participation whereof men became allied to the gods. And according to the Platonifts, heaven is not defined fo much by it's local fituation, as by it's purity. The pureft and most excellent fire, that is heaven, faith Ficinus. And again, the hidden fire that every where exerts it felf, he calls celeftial. He represents fire as most powerful and active, dividing all things, abhorring all compofition or mixture with other bodies. And, as foon as it gets free, relapfing inftantly into the common mass of celeftial fire, which is every where prefent and latent.

212. This is the general fource of life, fpirit, and strength, and therefore of health to all animals, who conftantly receive it's illapfes cloathed in air, through the lungs and pores of the body. The fame fpirit imprisoned in food and medicines, is conveyed into the ftomach, the bowels, the lacteals, circulated and fecreted by the feveral ducts, and diftributed throughout the fyftem (a). Plato in his Timæus enumerating the ignited juices, names wine in the first place, and tar in the fecond. But wine is preffed from the grape, and fermented by human induftry. Therefore of all ignited juices purely natural, tar or refin muft in his account be efteemed the first.

(a) 37, 42, 44.

213. The