their doctrines are exhibited, is not only likely to draw a veil, impenetrable to most eyes, over many of the inconsistencies of thought which they may involve, but to give a dexterous advocate infinite advantages in defending and vindicating these inconsistencies, if they should be brought under discussion.-When, on the other hand, this technical language has been supplanted by a different phraseology, and when the particular dogmas which it was employed to support come to be examined in separate and unconnected detail, error and absurdity carry along with them the materials of their own refutation; and the mysterious garb, under which they formerly escaped detection, serves only to expose them to additional ridicule. Such has, in fact, been the case with the scholastic theory of perception, which, after maintaining its ground, without any dispute, during a succession of centuries, is now represented as an extravagance of too great a magnitude, to have been ever understood by its abettors in the literal sense which their words convey. It would be happy for science, if some of those who have lately expressed themselves in this manner, did not conceal from superficial readers, and probably from themselves also, under a different, but equally hypothetical form of words, the very same fundamental mistake which revolts their judgment so strongly, when presented to them in terms to which they have not been accustomed.

The theory of Digby, too, when contrasted with that of his antagonist, is a historical document of considerable importance; exhibiting a specimen of the first attacks made on the system of the schoolmen, by the partisans of the new philosophy. The substitution of material images, instead of the ambiguous and mysterious species of Aristotle, by forcing the Peripatetics to speak out their meaning a little more explicitly, did more to bring them into discredit than the most acute and conclusive arguments of their opponents. Much about the same time, Dr Hooke expressed himself not less decidedly about the materiality of ideas or images; employing a mode of speaking on this subject not very unlike that of Dr Darwin. Priestley's language is somewhat different from this, being faithfully modelled after the hypothesis of his master, Dr Hartley. "If," says he, 66 as Hartley supposes, "the nerves and brain be a vibrating substance, all sensations and "ideas are vibrations in that substance; and all that is properly "unknown in the business, is the power of the mind to perceive "or be affected with these vibrations." In what manner Dr Priestley would have reconciled this inference with what I have already quoted from him with respect to the idea of extension, I presume not to conjecture,

As a further illustration of the notions which were prevalent with respect to the nature of sensible species, and that little more than a century ago, I shall quote a passage from a treatise, which,

notwithstanding its unpromising subject, was evidently the work of an author, deeply tainted, indeed, with the prejudices of his country and of his age, but of no inconsiderable learning and ingenuity. The treatise I allude to is entitled, "AEYTEPOZKONIA, or, a Brief Discourse concerning the Second Sight, common. "ly so called. By the Rev. Mr John Frazer, deceased, late "minister of Tirrie and Coll, and Dean of the Isles." (Edinburgh, printed by Mr Andrew Symson, 1707.)

66

The passage seems to me to deserve preservation, as a memo rial of the state of Scottish philosophy towards the end of the seventeenth century; and I willingly give it a place here, as the book from which it is extracted is not likely to fall in the way of many of my readers.

After mentioning a variety of anecdotes, concerning the illusions of imagination to which hypochondriacal persons are liable, when in a state of solitude, the author proceeds thus :—

"If you will ask, how cometh this to pass? Take notice of "the following method, which 1 humbly offer to your consider"ation. Advert, in the first place, that visible ideas or species 66 are emitted from every visible object to the organ of the eye, "representing the figure and colour of the object, and bearing "along with it the proportion of the distance; for sure, the ob 66 jects enter not the eye, nor the interjacent track of ground. "And a third thing, different from the eye and the object, and "the distant ground, must inform the eye. The species are con66 veyed to the brain by the optic nerve, and are laid up in the "magazine of the memory; otherwise, we should not remember "the object any longer than it is in our presence, and a remem"bering of those objects is nothing else but the fancy's receiving, or more properly, the soul of man by the fancy receiving, "these intentional species formerly received from the visible ob66 ject to the organ of the eye, and recondited into the seat of "the memory. Now, when the brain is in a serene temper, "these species are in their integrity, and keep their rank and file "as they were received; but when the brain is filled with gross "and flatuous vapours, and the spirits and humours enraged, "these ideas are sometimes multiplied, sometimes magnified, "sometimes misplaced, sometimes confounded by other species of "different objects, &c. &c. and this deception is not only inci❝dent to the fancy, but even to the external senses, particularly "the seeing and hearing. For the visus, or seeing, is nothing "else but the transition of the intentional species through the crystalline humour to the retiform coat of the eye, and judged

66

66

In consequence of the growing influence of the Cartesian philosophy, these words were then beginning to be regarded as synonymous.

"by the common sense, and conveyed by the optic nerve to the "fancy."

"Now, if these species formerly received and laid up in the 66 brain, will be reversed back from the same to the retiform coat "and crystalline humour as formerly, there is, in effect, a lively "seeing and perception of the object represented by these species, "as if de novo the object had been placed before the eye; for "the organ of the eye had no more of it before than now it has. "Just so with the hearing: it is nothing else but the receiving of "the audible species to that part of the ear that is accommodated "for hearing; so that when the species are retracted from the "brain to their proper organs (for example, the ear and the eye), "hearing and seeing are perfected, as if the objects had been pre"sent to influence the organ de novo. And it is not to be "thought that this is a singular opinion. For Cardanus, an "eminent author of great and universal reading and experience, "maintains this reversion of the species, and attributes his own "vision of trees, wild beasts, men, cities, and instructed battles, "musical and martial instruments, from the fourth to the seventh << year of his age, to the species of the objects he had seen for"merly, now retracted to the organ of the eye; and cites Aver" rocs, an author of greater renown, for the same opinion."See Cardanus de Subtilitate Rerum, p. 301.

"And it seems truly to be founded upon relevant grounds. I "have observed a sick person that complained of great pain and "molestation in his head, and particularly of piping and sweet "singing in his ears; which seems to have been caused by the "species of piping and singing which he had formerly heard ; but "were now, through the plethory of his head, forced out of the "brain to the organ of the ear, through the same nerve by which "they were received formerly; and why may not the same befal "the visible species as well as the audible? which seems to be "confirmed by this optic experiment: Take a sheet of painted 66 paper, and fix it in your window, looking steadfastly to it for a "considerable time; then close your eyes very strait, and open 66 your eyes suddenly, you will see the paintings almost as lively "as they were in the painted sheet, with the lively colours. This

compression of the eyes, by consent causes a compression of "the whole brain, which forces back the visible species of the "painted sheet to the organ of the eye through the optic nerve, "which will presently evanish if the reflectant did not help to preserve them. You may see then how much of these repre"sentations may be within ourselves, abstracting from any exter"nal agent or object, without the eye to influence the same."

Were it not for the credulity displayed by Mr Frazer, in various parts of his book, one would almost be tempted to consider

the foregoing theory as the effort of a superior mind combating the superstitious prejudices of his age, with such weapons as the erroneous philosophy of that age could supply. Perhaps the spirit of the times did not allow him to carry his scepticism farther than he did. A Lord President of our Supreme Court in Scotland (one of the most eminent and accomplished men whom this country has produced) is said to have been an advocate for this article of popular faith more than fifty years afterwards.

Note (I.) p. 125.

In the passage from Locke, quoted in the foot note, p. 124, a hint is given (very unworthy of his good sense) towards a new theory of the creation of matter. It is a remarkable circumstance, that a theory on the same subject was suggested to Priestley by certain speculations of his own, approaching very nearly to the doctrines of Boscovich ; a coincidence which strikes me as a strong additional presumption in favour of that interpretation which I have given to Locke's words.

"I will add in this place, though it will be considered more "fully hereafter, that this supposition of matter having (besides "extension) no other properties but those of attraction and re

pulsion, greatly relieves the difficulty which attends the suppo"sition of the creation of it out of nothing, and also the continual 66 moving of it, by a being who has hitherto been supposed to "have no common property with it. For, according to this hy"pothesis, both the creating mind, and the created substance, "are equally destitute of solidity or impenetrability; so that there can be no difficulty whatever in supposing that the latter may "have been the offspring of the former."-Disquisitions on Matter and Spirit, Vol. I. p. 23. (Birmingham, 1782.)

Note (K.) p. 148.

Notwithstanding the apology which I have offered for the word instinct, as it has been sometimes employed by writers on the Human Mind, I am perfectly sensible that it has been used, on various occasions, even by our most profound reasoners, with too great a degree of latitude. Examples of this might be produced, both from Mr Hume and Mr Smith; but I shall confine myself, in this note, to a passage from Dr Reid (by whose phraseology I was led to introduce the subject at present), in which he gives the name of instinct to the sudden effort we make to recover our balance, when in danger of falling; and to certain other instantaneous exertions which we make for our own preservation, in circumstances of unexpected danger.--(See his Essays on the Active Powers of Man, p. 174. 4to edit.)

In this particular instance, I agree perfectly (excepting in one

single point) with the following very judicious remarks long ago made by Gravesande :

"Il y a quelque chose d'admirable dans le moyen ordinaire "dont les hommes se servent, pour s'empêcher de tomber: car "dans le tems que, par quelque mouvement, le poids du corps "s'augmente d'un côté, un autre mouvement rétablit l'equilibre "dans l'instant. On attribue communément la chose à un in"stinct naturel, quoiqu'il faille necessairement l'attribuer à un art "perfectionné par l'exercice.

"Les enfans ignorent absolument cet art dans les premières "années de leur vie; ils l'apprennent peu à peu, et s'y perfec“tionnent, parce qu'ils ont continuellement occasion de s'y ex"ercer; exercice qui, dans la suite, n'exige presque plus aucune "attention de leur part; tout comme un musicien remue les "doigts, suivant les regles de l'art, pendant qu'il apperçoit à "peine qu'il y fasse la moindre attention."-Oeuvres Philosophiques de M. 'SGravesande, p. 121. Seconde Partie. Amster.

dam, 1774.

The only thing I am disposed to object to in this extract, is that clause where the author ascribes the effort in question to an art. Is it not manifestly as wide of the truth to refer it to this source as to pure instinct?

The word art implies intelligence; the perception of an end, and the choice of means. But where is there any appearance of either, in an operation common to the whole species (not excluding the idiot and the insane);-and which is practised as successfully by the brutes, as by those who are possessed of reason?

I intend to propose some modifications of the usual modes of speaking concerning this class of phenomena, when I come to contrast the faculties of Man with those of the lower animals.

Note (L.) p. 153.

Want of room obliges me to omit, at present, the illustrations destined for this note; and to refer to some remarks on secondary qualities, in the Philosophy of the Human Mind. See note (P.) at the end of that work; where I have attempted to explain the reference we make of the sensation of colour to the external object; the only difficulty which the subject seems to me to present, and of which neither Dr Reid nor Mr Smith have been sufficiently aware. (See Reid's Inquiry into the Human Mind; and the Essay on the External Senses, in Mr Smith's Posthumous Work.) Both of these writers have, in my opinion, been led to undervalue this part of the Cartesian Philosophy, by the equivocal use made in the common statements of it, of the names of secondary qualities; a circumstance which had long before been ably commented on by Malebranche. -D'Alembert saw the difficulty in all its extent, when he observed (speaking of the sen