difficult it may be in fome cafes, to diftinguish a first principle, yet there are certain marks, by which thofe reafonings that tend to the fubverfion of a first principle, may be detected, at least in all cafes of importance. However, we fhall offer a remark or two in answer to the question; which, tho' they should not appear perfectly unexceptionable, may yet throw light on the subject, and ferve to prepare the mind of the reader for fome things that are to follow.

First, then, if I wanted to certify myself concerning any particular fenfe or percipient faculty, that it is neither depraved nor defective, I fhould attend to the feelings or fenfations communicated by it; and obferve, whether they be clear and definite, and fuch as I am, of my own accord, difpofed to confide in without hefitation, as true, genuine, and natural. If they are fuch, I should certainly act upon them till I had some positive reafon to think them fallacious.-Secondly, I confider whether the fenfations received by this faculty be uniformly fimilar in fimilar circumstances. If they are not, I should fufpect, either that it is now depraved, or was formerly fo; and if I had no other criterion to direct me, fhould be much at a lofs to know whether I ought to trust the former or the latter experience; perhaps I fhould diftruft both. If they are uniform, if my present and my past experience do exactly coincide, I fhall then be difpofed to think them

both

both right. Thirdly, I confider, whether, in acting upon the fuppofition that the faculty in question is well-informed, I have ever been mifled to my hurt or inconvenience; if not, then have I good reason to think, that I was not mistaken when I formed that fuppofition, and that this faculty is really what I fuppofed it to be. - Fourthly, If the fenfations communicated by this faculty be incompatible with one another, or irreconcileable to the perceptions of my other faculties, I fhould fufpect a depravation of the former for the laws of nature, as far as my experience goes, are confiftent; and I am apt to believe that they are univerfally fo. It is therefore a prefumption, that my faculties are well informed, when the perceptions of one are quite confiftent with those of the rest, and with one another. In a ftate of folitude I must satisfy myself with these criteria; but in fociety I have access to another criterion, which, in many cafes, will be reckoned more decifive than any of thefe, and which, in concurrence with thefe, will be fufficient to banish doubt from every rational mind.

I compare my fenfations and notions with thofe of other men; and if I find a perfect coincidence, I fhall then be fatisfied that my fenfations are according to the law of human nature, and therefore right. — To illuftrate all this by an example:

I want to know whether iny fense of feeing be a well-informed faculty. - First, I

have reason to think that it is; because my eyes communicate to me fuch fenfations as I, of my own accord, am disposed to confide in. There is fomething in my perceptions of fight fo diftinct, and fo definite, that I do not find myself in the least disposed to doubt whether things be what my eyes represent them. Even the obfcurer informations of this faculty carry along with them their own evidence, and my belief. I am confident, that the fun and moon are round, as they appear to be, that the rainbow is arched, that grafs is green, fnow white, and the heavens azure; and this I fhould have believed, tho' I had paffed all my days in folitude, and never known any thing of other animals, or their fenfes. Secondly, I find that my notions of the visible qualities of bodies are the fame now they have always been. If this were not the cafe; if where I faw greenness yesterday I were to fee yellow to day, I fhould be apt to fuppofe, that my fight had fuffered fome depravation, unlefs I had reason to think, that the object had really changed colour. But indeed we have fo ftrong a tendency to believe our senses, that I doubt not but in fuch a cafe I fhould be more difpofed to suspect a change in the object than in my eye-fight much would depend on the circumstances of the cafe. We rub our eyes

when we want to look at any thing with accuracy; for we know by experience, that motes, and cloudy fpecks, that may be re

moved by rubbing, do fometimes float in the eye, and hurt the fight. But if the alteration of the visible qualities in the external object be fuch as we have never experienced from a depravation of the organ, we should be inclined to trust our eye-fight, rather than to suppose, that the external object has remained unaltered. — Thirdly, No evil confequence has ever happened to me when acting upon the fuppofition, that my faculty of feeing is a well-informed fense: whereas, if I were to act on the contrary fuppofition, I fhould foon have caufe to regret my fcepticifm. I fee a poft in my way; by turning a little afide, I pafs it unhurt: but if I had fuppofed my fight fallacious, and gone ftraight forward, a bloody nofe, or fomething worfe, might have been the confequence. If, when I bend my course obliquely, in order to avoid the poft that feems to ftand directly before me, I were to run my head full against it, I should instantly suspect a depravation in my eye-fight: but as I never experience any misfortune of this kind, I believe that my fense of seeing is a well-informed faculty. - Fourthly, The perceptions received by this fenfe are perfectly confiftent with one another, and with the perceptions received by my other faculties. When I fee the appearance of a folid body in my way, my touch always confirms the teftimony of my fight; if it did not, I fhould suspect a fallacy in one or other of thofe fenfes, per

haps

haps in both. When I look on a line of foldiers, they all feem ftanding perpendicular, as I myself ftand; but if the men at the extremities of the line, without leaning against any thing, were to appear as if they formed an angle of forty-five degrees with the earth's furface, I fhould fufpect fome unaccountable obliquity in my vifion.- Lastly, After the experience of many years, after all the knowledge I have been able to gather, concerning the fenfations of other men, from reading, difcourfe, and obfervation, I have no reafon to think their fenfations of fight different from mine. Every body who ufes the English language, calls fnow white, and grafs green; and it would be in the highest degree abfurd to fuppofe, that what they call the fenfation of whitenefs, is not the fame fenfation which I call by that name. Some few, perhaps, fee differently from me. A man in the jaundice fees that rofe yellow which I fee red; a fhort-fighted man fees that picture confufedly at the distance of three yards, which I fee diftinctly. But far the greater part of mankind fee as I do, and differently from thofe few individuals; whofe fenfe of feeing I therefore confider as lefs perfect than mine. Nay, tho' the generality of mankind were fhort-fighted, ftill it would be true, that we, who are not fo, have the moft perfect fight; for our fight is more accurate in its perceptions, qualifies us better for the business of life, and coincides more VOL. I, exactly,

Z