nor on the general laws of motion, nor on the denfity or elafticity of a medium, but merely and altogether on the good pleasure of the Creator, in the original formation of things? From whence divers unaccountable and unforeseen motions may arife in the animal oeconomy; from whence alfo various peculiar and fpecific virtues may be conceived to arife, refiding in certain medicines, and not to be' explained by mechanical principles. For although the general known laws of motion are to be deemed mechanical, yet peculiar motions of the infenfible parts, and peculiar properties depending thereon, are occult and fpecific. - 240. The words attraction and repulfion may, in compliance with custom, be used where, accurately fpeaking, motion alone is meant. And in that fenfe it may be faid, that peculiar attractions or repulfions in the parts, are attended with specific properties in the wholes. The particles of light are vehement-* ly moved to or from, retained or rejected by objects. Which is the fame thing as to fay with Sir Ifaac Newton, that the particles of acids are endued with great attractive force (m), wherein their activity confifts; whence fermentation and diffolution; and that the most repellent are, upon contact, the most attracting particles. 241. Gravity and fermentation are received for two most extenfive principles. From fermentation are derived the motion and warmth of the heart and blood in animals, fubterraneous heat, fires, and earthquakes, meteors and changes in the atmosphere. And, that attracting and repelling forces operate in the nutrition and diffolution of animal and vegetable bodies, is the doctrine both of Hip (m) 202. pocrates pocrates and Sir Ifaac Newton. The former of thefe celebrated authors, in his treatise concerning diet or regimen, obferves, that in the nourishment of man, one part repells and another attracts. And again, in the fame treatise, two carpenters, faith he, faw a piece of timber; one draws, the other pushes; these two actions tend to one and the fame end, though in a contrary direction, one up, the other down: This imitates the nature of man: πνεῦμα τὸ μὲν ἕλκει, τὸ δὲ ὠθέει. 242. It is the general maxim of Hippocrates, that the manner wherein nature acts confifteth in attracting what is meet and good, and in repelling what is difagreeable or hurtful. He makes the whole of the animal œconomy to be adminiftred by the faculties or powers of nature. Nature alone, faith he, fufficeth for all things to animals. She knows of herself what is neceffary for them. Whence it is plain, he means a confcious intelligent nature, that prefides and moves the etherial fpirit. And tho' he declares all things are accomplished on man by neceffity, yet it is not a blind fate or chain of mere corporeal caufes, but a divine neceffity, as he himself exprefly calls it. And what is this but an over-ruling intelligent power that dif pofeth of all things? 243. Attraction cannot produce, and in that fense account for the phænomena, being it felf one of the phænomena produced and to be accounted for (n). Attraction is performed by different laws, and cannot therefore in all cafes be the effect of the elafticity of one uniform medium. The phænomena of electrical bodies, the laws and variations of magnetism, and, not to mention other kinds, even (n) 160, 235. P 2 gra gravity, is not explained by elafticity, a phæno menon not lefs obfcure than itself. But then, although it fhews not the agent, yet it fheweth a rule and analogy in nature to fay, That the folid parts of animals are endued with attractive powers, whereby from contiguous fluids they draw like to like; and that glands have peculiar powers attractive of peculiar juices (0) Nature feems better known and explained by attractions and repulfions, than by those other mechanical principles of fize, figure, and the like that is by Sir Ifaac Newton, than Descartes, And natural philofophers excel, as they are more or lefs acquainted with the laws and methods obferved by the author of nature. 244. The fize and fhape of particles and general laws of motion can never explain the fecretions without the help of attraction, obfcure perhaps as to it's caufe, but clear as a law. Numberless inftances of this might be given: Lemery the younger thought himself obliged to fuppofe, the particles of light or fire (contrary to all reafon) to be of a very grofs kind, even greater than the pores of the burnt limestone, in order to account for their being detained or imprisoned therein; but this phanomenon is easily reduced to attraction. There would be no end of enumerating the like cafes, The activity and force of ætherial spirit or fire by the laws of attraction, is imparted to groffer particles (p), and thereby wonderfully fupports the econony of living bodies. By fuch peculiar compofitions and attractions it feems to be effected, that denfer fluids can pafs where air itself cannot, (as oil through leather) and therefore through (0) 41. (p) 152, 163. the the nicest and fineft ftrainers of an animal or vege table. 245. The ancients had fome general conception of attracting and repelling powers (q) as natural principles. Galilæi had particularly confidered the attraction of gravity, and made fome difcovery of the laws thereof. But Sir Ifaac Newton by his fingu lar penetration, profound knowledge in geometry and mechanics, and great exactnefs in experiments, hath caft a new light on natural fcience. The laws of attraction and repulfion were in many inftances difcovered, and firft difcovered, by him. He thewed their general extent, and therewith, as with a key, opened feveral deep fecrets of nature, in the knowledge whereof he seems to have made a greater progrefs, than all the fects of corpufcularians together had done before him. Nevertheless, the principle of attraction itself is not to be explained by phyfical or corporeal caufes. 246. The Cartefians attempted to explain it by the nifus of a fubtil element, receding from the center of its motion, and impelling groffer bodies towards it. Sit Ifaac Newton in his later thoughts feems (as was before obferved) to have adopted fomewhat not altogether foreign from this notion, afcribing that to his elastic medium (r) which Defcartes did to his fecond element. But the great men of antiquity refolved gravity into the immediate action of an intelligent incorporeal being. To which alfo Sir Ifaac Newton himself attefts and subscribes, although he may perhaps fometimes be thought to forget himself, in his manner of speaking of phyfical agents, which in a strict sense are none at all; and in fuppofing real forces to exift in bodies, in (g) 241, 242. (r) 237, 238. which which, to fpeak truly, attraction and repulfion fhould be confidered only as tendencies or motions, that is, as mere effects, and their laws as laws of motion. 247. Though it be fuppofed the chief bufinefs of a natural philofopher to trace out causes from the effects, yet this is to be understood not of agents (s) but of principles, that is, of component parts, in one fenfe, or of laws or rules, in another. In ftrict truth all agents are incorporeal, and as fuch are not properly of phyfical confideration. The Aftronomer, therefore, the Mechanic, or the Chemift, not as fuch, but by accident only, treat of real caufes, agents or efficients. Neither doth it feem, as is fuppofed by the greateft of mechanical philofophers, that the true way of proceeding in their fcience is, from known motions in nature to inveftigate the moving forces. Forafmuch as force is neither corporeal, nor belongs to any corporeal thing (t); nor yet to be discovered by experiments or mathematical reafonings, which reach no farther than difcernible effects, and motions in things paffive and moved. 248. Vis or force is to the foul, what extenfion is to the body, faith faint Augustin, in his tract concerning the quantity of the Soul; and without force there is nothing done or made, and confequently there can be no agent. Authority is not to decide in this cafe. Let any one confult his own notions and reason, as well as experience, concerning the origin of motion, and the refpective natures, properties, and differences of foul and body, and he will, if I mistake not, evidently perceive, that there is nothing active in the latter. Nor are they natural (s) 155. (+) 220. agents |