ence but that it is lefs diftinct than formerly *. This indiftinct fecondary perception of an object, is termed an idea. And therefore the precise and

* This experiment, which every one may make and reiterate till entire fatisfaction be obtained, is of greater importance than at first view may appear; for it ftrikes at the root of a celebrated doctrine that for more than two thoufand years has mifled many philofophers. This doctrine as delivered by Ariftotle is in fubftance, "That of every object of thought there must be fome form, "phantafm, or fpecies, in the mind; that things fenfible are per"ceived and remembered by means of fenfible fpecies, and things intelligible by intelligible fpecies; and that thefe fpecies or phantafms have the form of the object without the matter, as "the impreffion of a feal upon wax has the form of the feal with❝out its matter." The followers of Aristotle add, "That the "fenfible and intelligible fpecies of things, are sent forth from the

things themselves, and make impreffions upon the paffive in"tellect, which impreffions are perceived by the active intellect." This notion differs very little from that of Epicurus, which is, "That all things fend forth, conftantly and in every direction, "flender ghofts or films of themselves, (tenuia fimulacra, as ex"preffed by his commentator Lucretius); which striking upon the

mind, are the means of perception, dreaming," &c. Des Cartes, bent to oppofe Ariftotle, rejects the doctrine of fenfible and intelligible fpecies; maintaining however the fame doctrine in effect, viz. That we perceive nothing external but by means of fome image either in the brain or in the mind: and these images he terms ideas. According to thefe philofophers, we perceive nothing immediately but our own phantafms or ideas; and from thefe we infer, by reafoning, the existence of the external objects of which they are phantafms or ideas. Locke adopts this doctrine, and therefore employs almost the whole of his book about ideas. He holds that we cannot perceive, remember, nor imagine, any thing, but by having an idea or image of it in the mind. He a

grees

and accurate definition of an idea, in contradiftinction to an original perception, is, "That "perception of a real object, which is raised in "the

grees with Des Cartes, that we can have no knowledge of things external, but what we acquire by reafoning upon their ideas or images in the mind; taking it for granted, that we are conscious of these ideas or images, and of nothing else. Those who talk the moft intelligibly explain the doctrine thus: When I fee in a mirror a man standing behind me, the immediate object of my fight is his image, without which I could not fee him: in like manner, when I fee a tree or a house, there must be an image of these objects in my brain or in my mind; which image is the immediate object of my perception, and by means of that image I perceive the external object.

One would not readily fufpect any harm in this ideal system, further than leading us into a labyrinth of metaphyfical errors in order to account for our knowledge of external objects, which is more truly accounted for by fimple perception. And yet fome late philofophers have been able to extract from it death and destruction to the whole world, levelling all down to a mere chaos of ideas. Dr Berkeley, upon the authority of the philofophers named, taking for granted that we cannot perceive any object but what is in the mind, difcovered, that the reafoning employ'd by Des Cartes and Locke to infer the existence of external objects, is inconclusive; and upon that discovery ventured, against common sense, to an. nihilate totally the material world. And a later philofopher difcovering, that Berkeley's arguments might with equal fuccefs be applied against immaterial beings, ventured ftill more boldly to reject both by the lump; leaving nothing in nature but images or ideas floating in vacuo, without affording them a fingle mind for shelter or fupport.

When fuch wild and extravagant confequences can be drawn from the ideal fyftem, it might have been expected, that no man who is not crazy would have ventured to erect fuch a fuperftruc

ture,

"the mind by the power of memory." Every thing one is confcious of, whether internal or external, paffions, emotions, thinking, refolving,

willing,

ture, till he should first be certain beyond all doubt of a folid foundation. And yet upon examination, we find this foundation to be no better than a fhallow metaphyfical argument, viz. “That "6 no being can act but where it is; and, confequently, that it canre not act upon any subject at a distance." This argument poffeffes indeed one eminent advantage, that its obfcurity, like that of an oracle, is apt to impofe upon the reader, who is willing to confider it as a demonftration, because he does not clearly fee the fallacy. The best way to give it a fair trial, is to draw it out of its obfcurity, and to state it in a clear light, as follows. "No ob• "ject can be perceived unless it act upon the mind; but no distant "object can act upon the mind, becaufe no being can act but " where it is; and, therefore, the immediate object of perception "must be something united to the mind, fo as to be able to act up

on it." Here the argument completed in all its parts feems to be juftly ftated; and from it is derived the fuppofed neceffity of phantafms or ideas united to the mind, as the only objects of perception. It is fingularly unlucky for this argument, that it con cludes directly against the very fyftem of which it is made the only foundation. In that fyftem it is fuppofed, that phantafims or ideas are raised in the mind by things at a distance; and if things at a distance cannot act upon the mind, as is endeavoured to be proved by the argument under confideration, the fyftem must be false. But the folid answer to this argument is, that it affumes a propo. fition as true, without evidence, viz. That no object can be perceived unless it act upon the mind. This propofition undoubtedly requires evidence, for it is not intuitively certain. And, therefore, till the propofition be demonftrated, every man without fcruple may trust to the conviction of his fenfes, that he hears and fees things at a distance.

It is true, indeed, that to enable us to perceive diftant objects,

nature

willing, heat, cold, &c. as well as external ob jects, may be recalled as above, by the power of memory*.

15. The

nature employs intermediate means. In order to fee a tree, for example, rays of light must come from the tree to my eye, forming a picture upon the retina tunica: but the object perceived is the tree itself, not the rays of light, nor the picture. In this manner diftant objects are perceived, without any action of the object upon the mind, or of the mind upon the object. Hearing is in a fimilar cafe: the air put in motion by thunder, makes an impression upon the drum of my ear; but this impreffion is not what I hear, it is the thunder itself by means of that impreffion.

With respect to vision in particular, we are profoundly ignorant by what means and in what manner the picture on the retina tunica contributes to produce a fight of the object. One thing only is clear, that as we have no consciousness of that picture, it is as natural to conceive that it fhould be made the inftrument of discovering the external object, as of difcovering itself only, and not the external object.

Upon the chimerical confequences drawn from the ideal system, I fhall make but a single reflection. Nature determines us neceffarily to rely on the veracity of our fenfes; and upon their evidence, the exience of external objects is to us a matter of intuitive knowledge and abfolute certainty. Vain therefore is the attempt of Dr Berkeley and of his followers, to deceive us, by a metaphysical subtilty, into a disbelief of what we cannot entertain even the flighteft doubt.

From this definition of an idea, the following propofition muft be evident, That there can be no fuch thing as an innate idea. If the original perception of an object be not innate, which is obvious, it is not lefs obvious, that the idea or fecondary perception of that object cannot be innate. And yet, to prove this felf-evident propofition, Locke has bestowed a whole book of his treatise upon hu. man understanding. So neceffary it is to give accurate definitions,

and

15. The original perceptions of external objects, are either fimple or complex. Some founds are fo fimple as not to be refolvable into parts, and the perception of fuch founds must be equally fo: the like with respect to the perception of certain taftes and fmells. A perception of touch, is generally compounded of the more fimple perceptions of hardness or foftnefs, joined with fmoothnefs or roughness, heat or cold, &c. But of all the perceptions of external fenfe, that of a visible object is the most complex; because the eye takes in more particulars than any other organ. A tree is compofed of a trunk, branches, leaves: it has colour, figure, fize. Every one of these feparately produceth a perception in the mind of the fpectator, which are all combined into the complex perception of the tree.

16. The original perception of an object of fight, is more complete, lively, and distinct, than that of any other object. And for that reafon, an idea or fecondary perception of a visible object, is alfo more complete, lively, and diftinct, than that of any other object. A fine paffage in music, may, for a moment, be recalled to the mind with tolerable accuracy; but, after

Dr

and so preventive of difpute are definitions when accurate. Berkeley has taken great pains to prove another propofition equally evident, That there can be no fuch thing as a general idea: all our original perceptions are of particular objects, and our fecondary perceptions or ideas must be equally so.

the