장음표시 사용
571쪽
2o8. But these dissiculties may be got over by considering in the firct
place, that visibie potnis a re not mathematical potnis, and consequently that we are not to suppose every potnt of space a radiat ing poliat. Se- condiy, by granting that many rays do resis' and intercepi ea ch other, notis illi standing whicli the adt of vision may be persorine l. Since ase very potnt of the object is not seen, so it is not necessary that rays Dome very sucti potnt arrive at the eye. We osten see an o est, though more dimiy, when many rays are intercepted by a grosi medium. 2O9. Besides, we may suppose the particles of light to be indefinitelysmali, that is as sinati as we plea se, and their aggregate to bear as Malla proportion to the void as We plea se, there being nothing in this that
contradicts the phaenomena. And there needs nothing more, in order toconceive the possibili ty of rays pasting sto in and to ali visibie potnis, although they be not incorporeat. Suppo se a hundred poris placed rounda circular sea, and stips sat ling stom each pori to e very other; the largerthe sea, and the smaller the vesseis a re supposed, the lesis danger will therebe of their stri hing against each other. But as there is by hypothesis noli mited proportion be tween the sea and the ships, the void and solid particles of light, so there is no dissicut ty that can oblige us to conclude thesen's light incorporeal Dom iis Dee passage; especialty When there a re somany clear proose of the contrary. As sor the dissicut ty, theresore, attending the supposit ion os a sphere studded with eyes looking at cachother, this is removed only by supposing the particles of light exceedingsmali relatively to the empty spaces. aio. Plotinus supposeth, that fio m the sun's light whicli is corporeat there si rings sortii another equivocat light whicli is incorporeat, and as it were the brightnese of the forme r. Marcilius Ficinus also observing itto he a doctrine in the Timaeus of Plato that there is an occuli fite orspirit dissu sed througho ut the universe, intimates that this sanae occult
572쪽
invisibi e sire or light is, as it were, the si glit os the mundane foui. AndPlotinus in his fourth AEne id me eth it to be his opinion, that the woridseeth itself and ali iis paris. The Platonic philosophers do wonderiailyresine u pon light, and soar very high : Dom coal to flame ; Dom flame tolight: Dom this visi ble light to the occuli light of the celestial or mundane Qui, whicli they supposed to pervade and agitate the substance of
the universe by iis vigorous and expansive motion. 21 I. Is we may belle ve Diogenes Laertius, the Pythagorean philos phers thought there was a certa in pure heat or fi re, Which had semewhat divine in ii, by the participation whereos men beca me allied to the God s. And according to the Platonisis, heaven is not defined se much by iis localsit uation, as by iis purity. The purest and most excellent sire, that is heaven, salti, Ficinus. And again, the hidden fire that e very where exeris it is, he calis celestiat. He represenis sire as most powersul and active, dividing ali things, abhorring ali composition or mixture with otherbodies. And, as seon as it geis free, relapsing instantly in to the commonmasi os celestiat sire, whicli is every where present and latent. 212. This is the generat so urce of li se, spirit, and strength, and there- re, of health to ali animais, who constantly receive iis illapses cloathedin air, through the lungs and pores of the hody. The fame spirit imprisone d in od and medicines, is conveyed in to the stomach, the boweis, the lacteais, circula ted and secreted by the severat ducts, and distris buted througho ut the system '. Plato in his Timaeus en merating the igni ted juices, names wine in the first place, and tar in the second. Butwine is pressed hom the grape, and fermented by human industry. Theresore os ali igni ted juices purely naturat, tar or resin must in his aer count be esteemed the sirst.
573쪽
et I a. The vivisting luminous aether exist s in ali places, even the darkest caverns, as is evident hom heiace, that many animais see in thosedarli places, and that fi re may be Lindled in them by the collision or attritionos bodies. It is also known that certa in persons have fits of seeing in thedarh. Tiberius was se id to have had this faculty or distemper. I myselfhnew an ingenio us man who had experienced ii severat times in himself And Dr. Willis in his tract de sanguinis accentione mentions a nother of his own knowledge. This luminous aether or spirit is there re se id by Virgil, to nourish or cheristi the innermost carth, as weli as the hea vens and celestiat hodies. Princiso caelum ac terras, camposque liquentes. Lucentemque globum Lunae, Titaniaque oba Spiritus in tus alit.
2I . The principies of motion and vegetation in living bodies stemto be deliberations seo in the invisibie fire or spirit of the universe '. Whicli, though present to ali things, is not neverthelesi one Way received by ali , but varioussy imbibed, attracted, and secreted by the fine capillaries, and exquisii te strat ners in the bodies of planis and animais, wherebyit hecomes miged and deta ined in their juices.
glandular vesseis admit Do m the common mase of the blood, only such juices as are homogeneous to those, with whicli they were originalty im-hued. How they came to be so imbued doth not appear. But thus much is plain ; that fine tubes attract fluids, that the gland s are fine iubes, and that they attract very different j uices from the common musi. The fame holds also with regard to the capillary vesseis ' of vegetabies, it beinet evident that through the fine stra iners in the leaves and ali over
574쪽
the body of the plant, there be juices or suids of a particular hind dra nin, and separated hom the common masi of air and light. And that themost elaborate spirit, is hereon the character or distinguis hing virtve and properties of the plant depend, is os a luminous' and volatile nature, heing tost or esca ping into air or aether, frona essentiat olis and odorifero us a ters, without any sensibie diminution of them. 216. As di fierent hinds of secret ed light or fire produce disserent e L. sences, Virtu es, or specific properties, so also disterent degrees of heat produce disterent efiecis. Thus one degree of heat Leeps the blood Domcoagulat ing, and another degree coagulates the blood. Thus a more violent fire hath been observed to set Dee and carry off that very lighi, whicha more moderate fire had introduced and fixed in the calcined regulus ofanti mony. In like manner, one Lind or quantity of this aetheriat fiery spirit may be congenial and friendly to the spirits of a man, while another may be nOXiOUS. 217. Aiad experience me eth this to be true. For the fermented spirit of wine or other liquors produceth irregular motions, and subsequent depressions in the animal spiriis. 'Whereas the luminous spirit lodgedand deta ined in the native balsam os pines and firs, is os a nature somild and benign and proportioned to the human constitution, as to warmwithout heatin g, to cheer but not inebriate, and to Produce a calm and steady joy like the esse in of good ne s, Without that sint ing of spirit swhicli is a subsequent esse 2 of ali sermented cordials . I may add, without ali other inconvenience, excepi that it may like any other medicine het alien in too great a quantity sor a nice stomach. In whicli case it mayhe right, to tessen the dose, or to talie it only once in the four and twenty
575쪽
and rejoice in iis benign and com sortabie spirit. 2I8. Tar water serving as a vehicle to this spirit is both diu retic and diaphoretic, but seems to work iis principat effect by assisting the vis vitae,
RS an alterative and cordiat, enabling nature by an accession os congenialspirit, to assimilate that which could not be assimilated by her properforce, and so to subdue the fomes morbi. And this mould stem in most
cases the best and Diast course. Great evacuations weaken nature a Sweli as the dis aQ. And it is to be sed red that they who u se salivations and copious bieed ings, may, though they should reco ver of the distem per, in their Whole life be ne ver able to reco ver of the remedies. 2I9. It is true in deed, that in chronical cases there is ne ed of time tocomplete a cure, and yet I have linown this tar-water in disorders of thel ungs and stomach to prove a very speedy remedy, and to allay the anxi- ety and heat of a se ver in an instant, giving ea se and spiriis to the pati-cnt. This I have osten experien ced, not without surpri se at secing these falutary effects sollo immedia tely in a se ver on tali ing a glase of tarwater. Such is the force of these active vivisting principies containedin this balsam. 22o. Force or power, strictly speat in g, is in the agent alone who imparis an equivocat force to the invisit ble elementary fire, or animal spirit of the worid, and this to the igni ted hody or visibie fame, whicli producem the sense of light and heat. ln this cha in the fir and last lini sare allo ed to be incorporeal: the two intermediate are corporeat, beingcapable of motion, rarefaction, gravity, and other qualities of hodies. itis fit to distinguim these things, in order to avo id ambigui ty concerning
576쪽
ceptation, or vulgar sense past for si re, yet it is not the pure elementary 'fire in the second or philosophic sense, lach as was underctood by the seges of ant qui ty, and such as is collected in the secus os a burning glasi; much lest is it the vis, force, or power of burning, destroying, calcining, melling, vi trisying, and rai sing the perceptions of light and heat. Thisis truly and reatly in the incorporeat agent, and not in the vital spirit of the Universe. Motion, and even power in an equivocat sense, may be und in this pure aetheriat spirit, whicli ignites hodies, but is not it self the igni ted body, being an instrument or medium ' by. hicli the realagent doth operate on grosser bodies. aget. It hath been merued in Sir Isaac Newton's optics, that light is notreflected by impinging on bodies, but by so me other cause. Anil to hi mit stem S probabie, that as many rays as impinge on the solid paris of bo- dies, a re not reflected but sti fled and retained in the hodies. And it is certain, the great porosi ty of ali linown hodies affords room for much of this light or fire to be lodged there in . Gold it self the most solid os alimetal8, seems to have far more pores than solid paris, fio m water be ingi ressed through it in the Florenti ne experiment, stom magnetic em uvia passing, and stom mercury entering iis pores se freely. And it is admitted that water though impossibie to be compressed hath at least sorty times more pores than solid paris. And as ac id particles, joinedwith those of earlli in certa in proportion , are se closely uni ted withthem, as to be quite hid and lost to ali appea rance, as in mercurius dulcis
577쪽
and common sulphur, se also may we conceive the particles of light orsi re to be absorbed and latent in grosser hodies.stas. It is the opinion of Sir Isaac Newton, that semewhat unlino ure mains in vacuo, when the air is exhausted. This unknown medium he calis aether. He supposeth it to be more subtile in iis nature, and more Mist in iis motion than light, Deely to pervade ali bodies, and by iis immense elastici ty to be expanded throughout ali the heavens. Ita densi ty is supposed greater in Dee and open spaces, than With in the pores of compaci bo dies. And, in passing Dom the celestial bodies to great distances, it is supposed to grow denser and denser continuat ly ; and
there by cause those great hodies to gravitate to ardS One another, and their respective paris to wards their centers, c very body ende avo uring topasi stom the denser paris of the medium to ardS the rarer.22 . The extreme minutenesi of the paris of this medium and the
Veiosi ty of their motion, together with iis gravi ty, densi ty and elastic force, are thought to qualisy it for being the cause of ali the natural motions in the universe. To this cause a re ascribed the gravi ty and cohesionos hodies. The refraction of light is also thought to proceed sto in thedisserent densi ty and elastic force of this aetheriat medium in disserent Places. The vibrations of this medium alternately concurring With, orobstructing the motions of the rays of light, a re suppo sed to produce thefits of east reflexion and transmisson. Light by the vibrations of this
medium is thought to communicate heat to bodies. Animal motion and sensation a re also accounted for by the vibrating motions of this aetherialmedium, propaga ted through the solid capillaments of the nerves. In aword, ait the phaenomena and properties of bodies, that were bes ore attribu ted to attraction, upon later thoughis seem ascribe d to this aether, together With the various attractions them lues.
578쪽
et 23. But in the philosophy of Sir Isaac Newton, the sits as they a re
called) of easy transmission and reflexion, stem a s weli accounted forby vibrations excited in bodies by the rays of light and the refraction oflight by the attraction os hodies. To explain the vibrations of light bythoseos a more subtile medium, stem san Uncouth explication. And gratavi ty seems not an effect of the densii ty and elastici ty os aether, but ratherto be produced by so me other cause; Whicli Sir Isaachimself insinuatesto have been the opinion even of those ancient S Who toOh vacuum, atoms, and the gravi ty of atoms for the principies of their philosophy, tacit ly attributing as he weli observes gravi ty to have so me other causedistinin frona matter, fio m atoms and consequently, DOm that homoge-geneous aether or elastic fluid. The elasticity of whicli fluid is supposed to depend upon, to be desined and mea sured by iis densi ty ; and this by the quantity of matter in one particle, multiplied by the nUmber of particles contained in a gi ven space; and the quantity of matter in any one particie to be determined by iis gravi in Mould not there re gravi tyseem the original proporty and sirst supposed i On the other hand, ifforce he considered as prescinded Dom gravi ty and matter, and as existingonly in potnis or centers, what can this amo unt to but an abstraci spi rituat incorporeat forco tet 26. It doth not stem necesiary fio m the phaenomena, to suppose anymedium more active and subtile than light or fire. Light being allowedio move at the rate of abo ut ten millions of mileS in a minui g, what occasion is there to conceive another medium os still smal Ier and more movia
able paris. Light or fire stem the same With aether. So the ancients underctood, and so the Greeli word implies. It pervades ali things', iscvery where present. And this fame subtile medium according to iis vario uS qUantities, motions and determinations, me eth it self in disse erat effects or appearances, and is aether, light or fire.
579쪽
stet . The particles of aether fly a funder With the greatest sorce, there re, when uni ted they must saccording to the Newtonian doctrine
attract each other with the greatest force ; there re they a re acids ' orconstitute the acid; but this uni ted with earthy paris maheth aikali, as Sir Isaac teacheth in his tract de acido ; aikali, as appe ars in cantha rides and lixivial salis, is a caustic; causties a re fire; there re acidis fire; there re aether is fire; and is sire, light. WC are not there fore obliged to admit a neis medium distinct from light, and of a sinerand more exquisii te substance, for the explication os Phaenomena, whichappear to he as welb explained Without it. HOW can the densib orelastici ty of aether account sor the rnpid flight of a ray of light froni thelan, stili Mister as it goes farther stom the sun t Or h OK can it aceount for the various motions and attractions os disserent bodies Θ Why olland water, mercury and iron repet, or Why Other bodies attra et eae liother i or why a parti cle of light should repet on one fide and attract onthe other, as in the case of the istandic crystal t To explain cohesion by hamate atoms is accounted ignotum per ignotius. And is it not as muctiso to account sor the gravi ty of bodies by the elastici y of aether tet et 8. It is one thing to arrive at general la s Os nature hom a contem plation of the phaenomena; and another to frame an hypothesis, and Do m the ncci deduce the phaenomena. Those Who supposse epicycles, and by them expla in the motions and appe arances of the planeis, may notthere re he thought to have disco vered principies true in fact and naturo. And albeit we may noni the premisses inser a conclusion, it will not foulo , that we can urgue reciprocatly, and Dom the conclusion inser the premi ses. For instance, supposing an elastic suid, whose constituent minute particles are equid istant f rom each other and of equat densities and diameters, and recede one frona another with a centris gal forcewhicli is in verssy as the distance of the centers, and admitting that Domsuch supposition it must solio N, that the densi ty and elastic force of such
580쪽
fluid a re in the inverse proportion of the space it occupies When com pressed by any force ; yet we cannot reciprocatly infer, that a fluid en dued with this property must theresere consist of such supposed equalparticles; for it would then solio , that the constituent particles of air
vere os equat densities and diameters ; Whereas it is certain, that air is an heterogeneous mast, containing in iis composition an infinite varietyos exhalatioris, seo in the disserent bOdies Whicli malae up this terraque- Ous globe. let et q. The phaenomena of light, animal spirit, muscular motion, sertamentation, vegetation, and Other natural operations, stem to require
nothing more than the intellectual and artificiat fi re os Heraclitus, Hippo crates, the Stoics ', and other ancients. Intellect, superadded to aethereat spirit, fire, or light, moves, and moves regularly, proceed ing, in amethod, as the Stoics, or increasing and diminis hing by measure, as Heraclitus expressed it. The Stoics held that fi re comprehended and includ-
As the forms of things have their ideat existe iace in the intellect, se itshould seem that seminal principies have their natural existence in thelight ', a medium consisting of heterogeneous paris, distering fio m eachother in divers qualities that appear to sense, and not improbably having
many original properties, attractions, repulsions and motions, the laris and natures Whereos a re in discerni ble to us, other i se than in their remote effecis. And this animaled heterogeneous fire mould Qem a more adequale cause, Whereby to expla in the phaenomena os nature, than oneuniform aetheriat medium.
ago. Aristolle in deed excepis against the elements heing anima ted. Yet nothing hin ters why that power of the foui, styled by him orloco motive, may not resti de therein, under the direction os an intelles ,