the most he, or anybody else, can prove in favour of his conclusion is, that we know nothing more of the mind than that it is a series of perceptions. Whether there is something in the mind that lies beyond the reach of observation; or whether perceptions themselves are the products of something which can be observed and which is not mind; are questions which can in nowise be settled by direct observation. Elsewhere, the objectionable hypothetical element of the definition of mind is less prominent :

...

"The true idea of the human mind is to consider it as a system of different perceptions, or different existences, which are linked together by the relation of cause and effect, and mutually produce, destroy, influence and modify each other. In this respect I cannot compare the soul more properly to anything than a republic or commonwealth, in which the several members are united by the reciprocal ties of government and surbordination, and give rise to other persons who propagate the same republic in the incessant changes of its parts."(I. p. 331).

But, leaving the question of the proper definition of mind open for the present, it is further a matter of direct observation, that, when we take a general survey of all our perceptions or states of consciousness, they naturally fall into sundry groups or classes. Of these classes, two are distinguished by Hume as of primary importance, All "perceptions," he says, are either "Impressions” or “Ideas.”

Under "impressions" he includes "all our more lively perceptions, when we hear, see, feel, love, or will;" in other words, "all our sensations, passions, and emotions, as they make their first appearance in the soul" (I. p. 15).

"Ideas,” on the other hand, are the faint images of impressions in thinking and reasoning, or of antecedent ideas.

Both impressions and ideas may be either simple, when they are incapable of further analysis, or complex, when they may be resolved into simpler constituents. All simple ideas are exact copies of impressions; but, in complex ideas, the arrangement of simple constituents may be different from that of the impressions of which those simple ideas are copies.

Thus the colours red and blue and the odour of a rose, are simple impressions; while the ideas of blue, of red, and of rose-odour are simple copies of these impressions. But a red rose gives us a complex impression, capable of resolution into the simple impressions of red colour, rose-scent, and numerous others; and we may have a complex idea, which is an accurate, though faint, copy of this complex impression. Once in possession of the ideas of a red rose and of the colour blue, we may, in imagination, substitute blue for red; and thus obtain a complex idea of a blue rose, which is not an actual copy of any complex impression, though all its elements are such copies.

Hume has been criticised for making the distinction of impressions and ideas to depend upon their relative strength or vivacity. Yet it would be hard to point out any other character by which the things signified can be distinguished. Any one who has paid attention to the curious subject of what are called "subjective sensations" will be familiar with examples of the extreme difficulty which sometimes attends the discrimination of ideas of sensation from impressions of sensation, when the ideas are very vivid, or the impressions are faint. Who has not "fancied" he heard a noise; or has not explained inattention to a real sound by saying, "I thought it was nothing but my fancy"? Even healthy persons are much more liable to both visual and auditory spectrathat is, ideas of vision and sound so vivid that they are taken for new impressions-than is commonly supposed; and, in some diseased states, ideas of sensible objects may assume all the vividness of reality.

If ideas are nothing but copies of impressions, arranged, either in the same order as that of the impressions from which they are derived, or in a different order, it follows that the ultimate analysis of the contents of the mind turns upon that of the impressions. According to Hume, these are of two kinds: either they are impressions of sensation, or they are impressions of reflection. The former are those afforded by the five senses, together with pleasure and pain. The latter are the passions or the emotions (which Hume employs as equivalent terms). Thus the elementary states of consciousness, the raw materials of knowledge, so to speak, are either sensations or emotions; and whatever we discover in the mind, beyond these elementary states of consciousness, results from the combinations and the metamorphoses which they undergo.

It is not a little strange that a thinker of Hume's capacity should have been satisfied with the results of a psychological analysis which regards some obvious compounds as elements, while it omits altogether a most important class of elementary states.

With respect to the former point, Spinoza's masterly examination of the Passions in the third part of the "Ethics" should have been known to Hume.1 But, if he had been acquainted with that wonderful piece of psychological anatomy, he would have learned that the emotions and passions are all complex states, arising from the close association of ideas of pleasure or pain with other ideas; and, indeed, without going to Spinoza, his own acute discussion of the passions leads to the same result, and is wholly inconsistent with his classification of those mental states among the primary uncompounded materials of conscious

ness.

If Hume's "impressions of reflection" are excluded from among the primary elements of consciousness, nothing is left but the impressions afforded by the five senses, with pleasure and pain. Putting aside the muscular sense, which had not come into view in Hume's time, the questions arise whether these are all the simple undecomposable materials of thought? or whether others exist of which Hume takes no cognizance?

Kant answered the latter question in the affirmative, in the "Kritik der reinen Vernunft," and thereby made one of the greatest advances ever effected in philosophy; though it must be confessed that the German philosopher's exposition of his views is so perplexed in style, so burdened with the weight of a cumbrous and uncouth scholasticism, that it is easy to confound the unessential parts of his system with those

we feel either of these opposite affections, and are elated by pride or dejected with humility when self enters not into the consideration there is no room either for pride or humility." That is, pride is pleasure, and humility is pain, associated with certain conceptions of one's self; or as Spinoza puts it :Superbia est de se præ amore sui plus justo sentire" ("amor" being "lætitia concomitante idea causæ externæ"); and "Humilitas est tristitia orta ex eo quod homo suam impotentiam sive imbecillitatem contemplatur."