all other subjects, is too clear and precise to admit of its being supposed that he has used a new phrase without attaching to it a new signification, or to permit the present writer to believe, as he fain would do, that a point of nomenclature is the only point of difference between himself and one from whom it is so difficult to differ without diffidence and self-distrust.

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CHAPTER III.

DAVID HUME AS A METAPHYSICIAN.

But the mischief lieth here; that when men of less leisure see them who are supposed to have spent their whole time in the pursuit of knowledge profess ing an entire ignorance of all things, or advancing such notions as are repugnant to plain and commonly received principles, they will be tempted to entertain suspicions concerning the most important truths which they had hitherto held sacred and unquestionable.-Berkeley's Hylas and Philonous.

IN no department of science is it possible for an enquirer to advance considerably beyond all his predecessors without serving as a light by whose aid his successors may advance somewhat beyond him. This is the only apology that I feel disposed to offer for the freedom with which I am about to criticize one who, having been, by judges so competent as Adam Smith and Professor Huxley, pronounced to be 'by far the greatest philosopher' and 'acutest thinker' of his own age, would, doubtless, be at least on a level with the greatest philosophers of the present age if he were living now. The veriest cripple that can manage to sit on horseback may contrive to crawl some few steps beyond the utmost point to which his steed has borne him, and, if those steps be uphill, may, by looking back on the course he has come, perceive where the animal has deviated from the right road. Yet he does not on that account suppose that his own locomotive power is in any respect to be compared to his horse's; neither need an annotator on Hume, when pointing to holes in his author's metaphysical coat, be supposed not to be perfectly aware that it is the strength,

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not of his own eyes, but of the spectacles furnished to him by his author, that enables him to perceive them.

The concentrated essence of Hume's metaphysics is to be found in 'An Enquiry concerning Human Understanding,' forming part of a volume of Essays which Hume published somewhat late in life, and which he desired. might ‘alone be regarded as containing his philosophical sentiments and principles.' To a formal, though necessarily rapid, examination of the results of this 'Enquiry,' the present chapter will be almost exclusively devoted. Often as the operation has been performed already, there are two reasons why its repetition here may not be without utility for, first, its subject is a treatise containing the germs of much subsequent and still current speculation which, in so far as it is merely a development of those germs, cannot but be infected by whatever unsoundness may be inherent in them; and, secondly, because the subject, hackneyed as it may seem, is so far from being exhausted, that there is scarcely one among the doctrines embodied in it to which, as I proceed at once to show, fresh objection, more or less grave, may not be taken by a fresh investigator.

To begin very near indeed to the beginning, let us take, first, the section of the 'Enquiry' which treats of the 'Origin of Ideas.' All the perceptions of the mind may, according to Hume, be divided into two classes, whereof the one consists of all those 'more lively perceptions,' termed by him indifferently Impressions or Sensations, which we experience when we hear, or see, or feel, or love, or hate, or desire, or will:' the other, of those 'less lively perceptions of which we are conscious when we reflect on any of the sensations above-mentioned,' and which are commonly denominated

thoughts or ideas. All our ideas or more feeble perceptions,' he continues, are copies of our impressions or more lively ones,' the entire creative power of the mind amounting to no more than the faculty of compounding, transposing, augmenting, or diminishing the materials afforded by the senses and experience.' So confident is he of the literal accuracy of this statement, as to proceed to intimate that whenever we find in conversation or argument 'a philosophical term employed seemingly without any idea or meaning,' we have only to enquire from what impression its idea, if it have one, is derived, when, if no impression can be adduced, we may be sure that no idea is present either. The only phenomenon opposed to this rule, which he professes himself able to think of, is that of a person who, of a colour-as, for instance, blue-with which he is familiar, is able to conceive a shade somewhat different from any of the shades which he has actually seen; but this instance he disregards as too singular to affect the general maxim, to which, as he might have added, it is not really an exception, any more than would be the power of a person who had never seen a mountain higher than Snowdon or Mont Blanc to conceive one as high as Chimborazo or Mount Everest, for, equally in both cases, the ideas are copies of sensible impressions, although of complex, not simple, ones-of colour and graduation in the first case, of size and increase in the second. Still, there is at least one genuine exception, which it is the more remarkable that Hume should have overlooked, as it may be said to have stared him in the face from the very subject-matter he was considering. Our idea of idea itself, from what sensible impression is that derived? We have just been told that the difference between an idea and a sensation is

'that the first is a copy of the second, a feeble copy of a lively original. The idea therefore is not itself a sensation; the copy is not itself an original. Neither consequently can the idea or notion which the mind proceeds to form of any of its previous ideas be derived from or be a copy of a sensation it cannot have entered the mind 'in the only manner by which,' according to Hume, 'an idea can have access to the mind, to wit, by actual feeling and sensation.'

Let me not be misunderstood. Let me not be supposed to be courting collision with the Berkleian thesis of the non-existence of abstract ideas. I do not for one moment doubt that all our general or class notions of sensible objects or events are merely concrete ideas of individual objects or events-that, for instance, whenever we talk of man or motion in general, we are really thinking of some particular man or motion, which, as possessing all properties common to all men or motions, serves as a representative of the entire genus. Neither am I prepared to deny, although scarcely either prepared to admit, that even of abstract qualities all our general or class notions are equally ideas of particular specimens of those qualities; that, when we speak, for instance, of virtue or vice in general, we are thinking of some particular exhibition of some particular kind of virtue or vice. Nay, I am not even concerned to deny that our idea of idea in general may possibly be a copy of some particular one of our previous ideas which, for the nonce, serves to represent all our other previous ideas. I limit myself to saying that our idea of idea in general, whether it be or be not itself an abstraction, is, at all events, not a copy of sensation. I admit that it thereby differs essentially from most, if not all, other general ideas. Possibly it may be only through my having