many ways to error, and but one to truth; and we see there are always fome, who, to enrich themselves, endeavour to pass counterfeit coin for Sterling. Befides, our greatest mistakes in judgment proceed from a cause of which we are not fufficiently aware; which is this: We attend so closely to the confequences, that we overlook the premiffes; and while we are so very careful to examine thofe, take these for granted. Hence we take propofitions to be really demonstrated, which have nothing but the air of demonstration, and are hereby led fometimes to give our affent to the greatest abfurdities. By these means, cunning and designing men, by falfely stating a case, or laying down falfe premiffes, and reafoning from them, draw true conclufions, which deceive unwary readers into a belief of the truth of the premiffes, when they are utterly falfe. And though these artifices have been often detected, the state of the cafe, and the premiffes proved to be false, and thence all the conclufions good for nothing; yet the notion of I know not what demonftration, once received, fo

runs

runs in, and fills the heads of the readers, that it is a difficult matter to beat it out, or perfuade them to re-examine the fubject. We ought therefore to take great heed, and be very careful what we admit for pinciples and data; especially in an affair of that consequence as philofophy; because on our fentiments of nature will be formed our notions of its author. To demonstrate, is to bring things under the cognifance of our fenfes, which fuppofes the things to be objects of fenfe. Mathematics are moft capable of demonftration, because the things they are converfant about, are really the objects of sense: the mind has immediate perception of the things themselves; fo the ideas taken from them are real and adequate, and its knowledge is in many cafes intuitive. "But the proofs in natural phi

lofophy cannot be fo abfolutely conclu"five as in the mathematics, the subject "of our contemplation being without us, " and not fo compleatly to be known." This the author of the view of Sir Isaac Newton's philofophy, in the paffage above, confesses; and at the conclufion fays, "To acquiefce

F

So

acquiefce in the explanation of any appearance, by afferting it to be a general power of attraction, is not to improve our knowledge in philosophy, but rather "to put a stop to our farther fearch." we have this gentleman's leave to make a further enquiry; and, in doing it, we must not only examine thoroughly the principles we go upon, but the means we have of coming at the knowledge of them; because, if it should happen that the mind of man has no natural powers of acquiring (without revelation) the knowledge of the caufe of motion, for inftance, while they think they are reafoning, they will prove only to be imagining.

ΜΕΝ may aim at forming ideas of fuch things, but this is only imagination. It is natural from fuppofed or real premiffes, to reafon falfely or truly; fuppofe this or that, and the consequences will be fo and fo: the reasonings in both cafes are just, but the evidence in one cafe is not true. He who supposes an imaginary agent performs an action, if he understand the action, may

reafon

reafon as justly upon that action, as if he knew the real agent. A man who gives the name of gravity, attraction, &c. to the cause of the operations of nature; as far as by observations he has difcovered, or imagines he has discovered these operations, so far he reafons as juftly as if he knew the real cause. But ftill this will not prove his imaginary powers to be the real ones. This being unknown, all he has found out, only amounts to this, that fomething does, or is the cause of fomething. Such a poor business is all our boafted knowledge and philofophy. By this it seems they have mistaken the actions for the agents, and have only discovered the effects, while they imagined they knew the causes. Calculating the velocity, &c. of a falling body, and supposing that it descends to the earth by gravitation, is not finding where it is, and what it is that gives it motion. Much lefs will it prove, that matter has any attractive virtue to draw other matter to it; which is giving it a power of acting where it is not prefent; a power they deny their Deus. To perfuade me there is a power

F 2

in

the

the earth to draw a ftone to it, and in the stone to obey and come to it, because I fee it fall to the ground, is the fame as to tell me a pendulum has motion in itself, becaufe, what? I fee it move. This I prefume would not be a fatisfactory answer to one who enquired after the mechanism of a clock. These gentlemen can fwallow tranfubftantiation from a Newton, though they strain at it from the Pope. They can believe that grofs bodies are convertible into light, and light into grofs bodies; earth into fire, et e contra; water into a stone *; and that falts, fulphurs, tinctures, fludge, loam, clay, fand, ftones, corals, and other earthly fubftances, are formed from the vapours which arise from the fun, fixed ftars, and the tails of comets, (See Newton's Principia, p. 526.). I fay, the man who, under the character of a philosopher, imposes such idle figments upon his readers, puts a greater violence upon, and offers a greater affront to their fenfes and reason, than he who preaches tranfubftan

Optics, Lat. edit. 1719, p. 378. English edit. 1721, P. 349.

tiation ;