་

gravity, is not explained by elafticity, a phænomenon not lefs obfcure than itself. But then, although it fhews not the agent, yet it fheweth a rule and an alogy 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 thofe other mechanical principles of fize, figure, and the like: that is, by Sir Ifaac Newton, than Defcartes. 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 shape of particles, and general laws of motion can never explain the fecretions without the help of attraction, obfcure perhaps as to its cause, 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 reason) 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 eafily 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 peconomy 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 niceft and finest strainers of an animal or vegetable.

245. The ancients had some general conception of attracting and repelling powers (q) as natural principles. Galilæi had particularly confidered the attraction of gravity, and made fome discovery of the laws thereof. But Sir Ifaac Newton by his fingular 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 discovered, and first discovered, by him. He fhewed their general extent, and therewith, as with a key, opened several deep fecrets of nature, in the knowledge whereof he seems to have made a greater progress, 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 causes.

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. Sir Ifaac Newton in his later thoughts feems (as was before observed) 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 fubscribes, 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 exist in bodies, in

(9) 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 business of a natural philofopher to trace out caufes 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 causes, agents or efficients. Neither doth it feem, as is fuppofed by the greatest of mechanical philofophers, that the true way of proceeding in their fcience is, from known motions in nature to investigate the moving forces. Forafmuch as force is neither corporeal, nor belongs to any corporeal thing (t); nor yet to be difcovered by experiments or mathematical reasonings, 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 Auguftin, 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 (1) 220.

(s) 155.

agents

agents or corporeal forces, which make the parti

cles of bodies to cohere. Nor is it the business of experimental philofophers to find them out.

249. The mechanical philofopher, as hath been already obferved, inquires properly concerning the rules and modes of operation alone, and not concerning the cause, forafmuch as nothing mechanical is or really can be a cause (u). And although a mechanical or mathematical philofopher may speak of abfolute fpace, abfolute motion, and of force as exifting in bodies, causing fuch motion and proportional thereto; yet what thefe forces are, which are fuppofed to be lodged in bodies, to be impreffed on bodies, to be multiplied, divided, and communicated from one body to another, and which feem to animate bodies like abftract fpirits or fouls, hath been found very difficult, not to fay impoffible, for thinking men to conceive and explain; as may be feen by confulting Borellus De vi percuffionis, and Torricelli in his Lezioni academiche, among other authors.

250. Nor, if we confider the proclivity of mankind to realize their notions, will it feem ftrange that mechanic philofophers and geometricians fhould, like other men, be misled by prejudice, and take mathematical hypothefes for real beings existing in bodies, fo far as even to make it the very aim and end of their science to compute or measure those phantoms; whereas it is very certain that nothing in truth can be measured* or computed, befide the very effects or motions themselves. Sir Ifaac Newton afks, Have not the minute particles of bodies certain forces or powers by which they act on

(u) 236, 247

This fubject is handled at large in my Latin tract De motu, published above twenty years ago.

one

one another, as well as on the particles of light, for producing moft of the phænomema in nature? But in reality, thofe minute particles are only agitated according to certain laws of nature, by fome other agent, wherein the force exifts and not in them, which have only the motion; which motion in the body moved, the Peripatetics rightly judge to be a mere paffion, but in the mover to be ivigya

or act.

251. It paffeth with many, I know not how, that mechanical principles give a clear folution of the phænomena. The Democritic hypothefis, faith doctor Cudworth, doth much more handfomely and intelligibly folve the phænomena, than that of Ariftotle and Plato. But things rightly confidered, perhaps it will be found not to folve any phænomenon at all. For all phænomena are, to speak truly, appearances in the foul or mind; and it hath never been explained, nor can it be explained, how external bodies, figures, and motions fhould produce an appearance in the mind. Those principles, therefore, do not folve, if by folving is meant affigning, the real, either efficient or final, cause of appearances, but only reduce them to general rules.

252. There is a certain analogy, conftancy, and uniformity in the phænomena or appearances of nature, which are a foundation for general rules: and thefe are a grammar for the understanding of nature, or that series of effects in the vifible world, whereby we are enabled to foresee what will come to pass, in the natural course of things. Plotinus obferves, in his third Ennead, that the art of prefaging is in fome fort the reading of natural letters denoting order, and that fo far forth as analogy obtains in the univerfe, there may be vaticination. And in reality, he that foretells the motions of the

pla