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 itself fo eafily without collifion, condenfation, rarefaction, or delay throughout the wafted space. These 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 its motion is not inftantaneous: that it is capable of condenfation, rarefaction, and collifion: that it can be mixed with other bodies, enter their compofition, and increase their weight (a). All which feem fufficiently to overthrow thofe 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 sphere, ftudded with eyes looking inwards one at another, it may perhaps seem hard to conceive, how diftinct rays from every eye fhould arrive at every other eye without juftling, repelling, and confounding each other. 208. But these 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, notwithftanding which the act of vision may be performed. Since as every point of the object is not feen, fo it is not neceffary that rays from every such point arrive at the eye. We often fee (a) 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 please, and their aggregate to bear as fmall a proportion to the void as we please, 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 vifible points, although they be not incorporeal. Suppofe 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 ftriking against each other. But as there is by hypothefis no limited proportion between 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 paces. 210. Plotinus fuppofeth, that from the fun's light which is corporeal, there fprings forth ano ther equivocal light which is incorporeal, and as it were the brightness 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 diffufed throughout the universe, 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 N •parts. parts. The Platonic philofophers do wonderfully refine upon light, and foar very high from coal to flame; from flame to light; from this visible light to the occult light of the celestial or mundane foul, which they fuppofed to pervade and agitate the fubftance of the univefe by it's vigorous and expanfive motion. 211. If we may believe Diogenes Laertius, the Pythagorean 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 reprefents fire as moft powerful and active, dividing all things, abhorring all compofition or mixture with other bodies. And, as foon as it goes free, relapfing inftantly into the common mafs 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 firft place, and tar in the fecond. But wine is preffed from the grape, and fermented by human industry. Therefore of all ignited juices purely natural, tar or refin muft in his account be efteemed the first. 213. The vivifying luminous æther exifts in all places, even the darkest caverns, as is evident from hence, that many animals fee in thofe dark places, and that fire may be kindled in them by the collifion or attrition of bodies. It is alfo known that certain perfons have fits of feeing in the dark. Tiberius was faid to have had this faculty or diftemper. I my felf knew an ingenious man, who had experienced it feveral times in himself. And doctor Willis, in his tract De fanguinis accenfione, mentions another of his own knowledge. This luminous æther or spirit is therefore faid by Virgil, to nourish or cherish the innermoft earth, as well as the heavens and celeftial bodies. Principio cœlum ac terras, campofque liquentes, Lucentemque globum Lunæ, Titaniaque aftra Spiritus intus alit. 214. The principles of motion and vegetation in living bodies feem to be delibations from the invifible fire or fpirit of the universe (a). Which, though prefent to all things, is not nevertheless one way received by all; but variously imbibed, attracted, and fecreted by the fine capillaries, and exquifite ftrainers in the bodies of plants and animals, whereby it becomes mixed and detained in their juices. 215. It hath been thought by fomes obfervers of nature, that the fine glandular veffels admit from the common mafs of the blood, only fuch juices as are homogeneous to thofe, with which they were originally imbued. How they came to be fo imbued doth not appear. But thus much is plain; that fine tubes attract fluids, that the glands are fine tubes, and that they attract very (a) 43, 157, 164, 171. N 2 diffe different juices from the common mass. The fame holds alfo with regard to the capillary veffels (a) of vegetables, it being evident, that through the fine ftrainers in the leaves and all over the body of the plant, there be juices or fluids of a particular kind drawn in, and feparated from the common mafs of air and light. And that the most elaborate fpirit, whereon the character or distinguishing virtue and properties of the plant depend, is of a luminous (b) and volatile nature, being loft or efcaping into air or æther, from effential oils and odoriferous waters, without any fenfible diminution of the fubject. 216. As different kinds of fecreted light or fire produce different effences, virtues, or specific properties, fo alfo different degrees of heat produce different effects. Thus one degree of heat keeps the blood from coagulating, and another degree coagulates the blood. Thus, a more violent fire hath been obferved to fet free and carry off that very light, which a more moderate fire had introduced and fixed in the calcined regulus of antimony. In like manner, one kind or quantity of this ætherial fiery fpirit may be congenial and friendly to the fpirits of a man, while another. may be noxious. 217. And experience fheweth this to be true. For the fermented fpirit of wine or other liquors produceth irregular motions, and fubfequent depreffions in the animal fpirits. Whereas the, luminous fpirit lodged and detained in the native balfam of pines and firs, is of a nature fo mild and benign, and proportioned to the human conftitution, as to warm without heating, to cheer but not ine (a) 30, 31, 33, 35, (b), 37, 43. briate, |