observes, must necessarily take for granted some principles not more certain nor more obvious than the thing to be proved; and therefore can add nothing to its authority with men who have duly weighed the nature of reasoning and of demonstrative proof. Nor is this all. Where scepticism is founded on a suspicion of the possible fallibility of the human faculties, the very idea of correcting it by an appeal to argument is nugatory; inasmuch as such an appeal virtually takes for granted the paramount authority of those laws of belief which the sceptic calls in question. The belief, therefore, of the existence of matter, is left by Dr. Reid on the very same footing on which Descartes found it; open, as it then was, and as it must for ever remain, to the sceptical cavils which affect equally every judgment which the human mind is capable of forming; but freed completely from those metaphysical objections which assailed it, as at variance with the conclusions of philosophy.

But although, in so far as the arguments of the Berkeleians is concerned, Dr. Reid's reasonings appear to me to be unanswerable, I am not completely satisfied that he has stated the fact on his own side of the question with sufficient fulness and correctness. The grounds of my hesitation on this point I propose to explain at some length, in the second chapter of this essay. In the mean time, I think it of still greater importance, to caution my readers against another misapprehension (equally remote with the former from truth) by which the Berkeleian controversy has been involved by some late writers, in additional obscurity.

*

2. In order to prepare the way for the remarks which are to follow, it is necessary to observe (for the sake of those who are little conversant with the history of natural philosophy, that, according to an ingenious theory, proposed about fifty years ago by Father Boscovich, the notions which are commonly entertained concerning the qualities of matter, are the result of very rash and unwarranted inferences from the phenomena perceived. The ultimate elements (we are taught) of which matter

*Theoria Philosophiæ Naturalis. (First published at Vienna, in 1758.)

is composed, are unextended atoms, or in other words mathematical points, endued with certain powers of attraction and repulsion; and it is from these powers that all the physical appearances of the universe arise. The effects, for example, which are vulgarly ascribed to actual contact, are all produced by repulsive forces occupying those parts of space where bodies are perceived by our senses; and therefore the correct idea that we ought to annex to matter, considered as an object of perception, is merely that of a power of resistance, sufficient to counteract that compressing power which our physical strength enables us to exert.

With regard to this theory, I shall not presume to give any decided opinion. That it is attended with some very puzzling difficulties of a metaphysical nature, must, I think, be granted by its most zealous advocates ; but, on the other hand, it can scarcely be denied, that the author, or his commentators, have been successful in establishing three propositions. 1. That the supposition of particles, extended and perfectly hard, is liable to strong, if not to insurmountable objections. 2. That there are no facts which afford any direct evidence in support of it. And, 3. That there are some indisputable facts which favor the opposite hypothesis. In proof of the last proposition, among a variety of other arguments, an appeal has been made to the compressibility and elasticity of all known bodies; to their contraction by cold; and to certain optical and electrical experiments, which show that various effects, which our imperfect senses lead us to ascribe to the actual contact of different bodies, are, in fact, produced by a repulsive power, extending to a real, though imperceptible distance from their surfaces. The same phenomena, therefore, may be produced by repulsion, which we commonly ascribe to contact; and if so, why not refer to the same cause all effects of the same nature? *

*The following passage in Locke, when considered in connexion with some others in his writings, would almost tempt one to think, that a theory concerning matter, somewhat analogous to that of Boscovich, had occasionally passed through his mind.- -"Nay, possibly, if we could emancipate ourselves from vulgar notions, and raise our thoughts as far as they could reach, to a closer contemplation of things, we might be able to aim at some dim and seeming conception, how matter VOL. IV. 12

A theory, essentially the same with this, has been proposed of late by different writers in this island, who seem to have been led to it entirely by their own speculations, without any knowledge of its having been previously started by another; and it has been in consequence of the particular view which some of them have taken of the subject, that the misapprehension which I am anxious at present to correct has chiefly arisen. In fact, the systems of Boscovich, and of Berkeley, have not the most remote relation to each other. The account, indeed, of some of the qualities of matter which is given in the former, is very different from that commonly entertained, but this account does not call in question the reality of matter, as an existence distinct. from the perceiving mind. It does not affect, in the

least, our notions of extension and figure; nor even those of hardness and softness, any further, than as it defines these qualities by the relation which they bear to our animal force. The resistance opposed to our efforts implies an existence distinct from ours, as much as the efforts we are conscious of making imply our own existence; and therefore, whether we proceed on the common notions concerning matter, or on the hypothesis of Boscovich, the authority of that law of our nature which leads us to ascribe to things external an inde

might at first be made, and begin to exist by the power of that eternal first Being.""But this being what would perhaps lead us too far from the notions on which the philosophy now in the world is built, it would not be pardonable to deviate so far from them as to inquire, so far as grammar itself would authorize, if the common settled opinion opposes it."-Essay on Human Understanding, Book iv. chap. x. § 18.

Whosoever chooses to examine the grounds upon which I have hazarded the foregoing observation, may compare the passage just quoted with what Locke has said of cohesion, in Book ii. chap. xxiii. §§ 23, 24, et seq. more particularly in §§ 26

and 27.

From the same passage, Dr. Reid conjectures, that "Locke had a glimpse of the system which Berkeley afterwards advanced, although he thought proper to suppress it within his own breast." (Essays on the Intell. Powers, p. 170.) I think it much more probable, from the hints he has dropped in other parts of his Essay, that he had some vague notion of a theory approaching to that of Boscovich. The following remark confirms me in this conjecture:

"Hardness consists in a firm cohesion of the parts of matter, making up masses of a sensible bulk, so that the whole does not easily change its figure. And, indeed, hard and soft are names that we give to things only in relation to the constitution of our own bodies; that being generally called hard by us, which will put us to pain sooner than change figure by the pressure of any part of our bodies; and that, on the contrary, soft, which changes the situation of its parts upon an easy and unpainful touch." Book ii. chap. iv. §4.-See Note (H.)

pendent and permanent existence, remains unshaken. According to Berkeley, extension and figure, hardness and softness, and all other sensible qualities, are mere ideas of the mind, which cannot possibly exist in an insentient substance.*

That the inference which I have now drawn against the scheme of idealism from the theory of Boscovich, is perfectly agreeable to the metaphysical views of that profound and original philosopher, appears from various passages in his works: in particular, from the following observations, which I translate literally from one of his supplements to the didactic poem of Benedictus Stay, De Systemate Mundi:

66

By the power of reflection, we are enabled to distinguish two different classes of ideas excited in our minds. To some of these we are impelled by a very powerful instinct, common to all men, to ascribe an origin foreign to the mind itself, and depending on certain external objects. Others, we believe with the most complete conviction to have their origin in the mind, and to depend on the mind for their existence. The instruments or organs by which we receive the first kind of ideas are called the senses: their external cause, or, as it is commonly called, the object, is denoted by the words matter and body. The source of the second class of our ideas (which we discover by reflecting on the subjects of our own consciousness) is called the mind or soul.

"In this manner we become acquainted with two different kinds of substances (the only substances of which we possess any knowledge;) the one, a sensible or perceptible substance; the other a substance endowed with the powers of thought and of volition. Of the existence of neither is it possible for us to doubt, (such is the force of those intimations we receive from nature ;) not even in those cases when, offering violence to ourselves, we listen to the suggestions of the Pyrrhonists

* A remark to the same purpose has been made by Mr. Smith, in his Essay on the External Senses. Whatever system may be adopted concerning the hardness or softness, the fluidity or solidity, the compressibility or incompressibility of the resisting substance, the certainty of our distinct sense, and feeling of its externality, or of its entire independency upon the organ which perceives it, or by which we perceive it, cannot, in the smallest degree, be affected by any such system."-Essays on Philosophical Subjects, p. 204.

and Egoists, and other sophistical perverters of the truth. Nay, even these sceptics themselves are forced to acknowledge, that whatever doubts they may have experienced in their hours of speculation, vanish completely when the objects of their doubts are presented to their senses.' ""*

I do not take upon me to defend the propriety of all the expressions employed in the foregoing passage. I quote it merely as a proof, that Boscovich himself did not conceive that his peculiar notions concerning the nature of matter had the slightest tendency to favor the conclusions of Berkeley. On the contrary, he states his dissent from these conclusions in the strongest and most decided 'terms; coinciding so exactly with Reid in the very phraseology he uses, as to afford a presumption that it approaches nearly to a correct and simple enunciation of the truth.

In the foregoing remarks on Boscovich's theory, considered in contrast with that of Berkeley, I have had an eye chiefly to some speculations of the late Dr. Hutton; a philosopher eminently distinguished by originality of thought; and whose writings could not have failed to attract much more notice than they have yet done, if the great variety of his scientific pursuits had left him a little more leisure to cultivate the arts of composition and of arrangement. It would be fortunate, in this respect, for his literary fame, if the same friendly and skilful hand which has illustrated and adorned his geological researches, would undertake the task of guiding us through the puzzling, but interesting labyrinth of his metaphysical discussions.

The following is the conclusion of Dr. Hutton's argument concerning hardness and incompressibility:

"In thus distinguishing things, it will appear, that incompressibility and hardness, i. e. powers resisting the change of volume and figure, are the properties of an external body; and that these are the essential qualities of that extended, figured thing, so far as it is only in these resisting powers that the conceived thing, termed body, is judged to subsist.

* Romæ, 1755, T. i. p. 331.