not instantly group together all the sounds and all the colours, all the touches and all the smells; but, dividing what is given together, single out a certain sound or smell as belonging together with a certain colour and feel, similarly singled out from the rest, to what we call one thing. We might wonder, too -those at least who have made so much of association by similarity ought to wonder-that, say, the white of snow calls up directly, not other shades of white or other colours, but the expectation of cold or of powdery softness. The first step in this process has been the simultaneous projection into the same occupied space of the several impressions which we thus come to regard as the qualities of the body filling it. Yet such simultaneous and coincident projection would avail but little unless the constituent impressions were again and again repeated in like order so as to prompt anew the same grouping, and unless, further, this constancy in the one group was present along with changes in other groups and in the general field. There is nothing in its first experience to tell the infant that the song of the bird does not inhere in the hawthorn whence the notes proceed, but that the fragrance of the mayflower does. It is only where a group, as a whole, has been found to change its position relatively to other groups, and-apart from casual relations to be independent of changes of position among them, that such complexes can become distinct unities and yield a world of things. Again, because things are so often a world within themselves, their several parts or members not only having distinguishing qualities but moving and changing with more or less independence of the rest, it comes about that what is from one point of view one thing becomes from another point of view several-like a tree with its separable branches and fruits, for example. Wherein then, more precisely, does the unity of a thing consist? This question, so far as it here admits of answer, carries us over to temporal continuity.
d. Amidst all the change above described there is one thing comparatively 'dxedz our own body is both constant as a group Temporal and a constant item in every field of groups; and not Continuitn only so, but it is beyond all other things an object of continual and peculiar interest, inasmuch as our earliest pleasures and pains depend solely upon it and what affects it. The body becomes, in fact, the earliest form of self, the first datum for our later conceptions of permanence and individuality. A continuity like that of self is then transferred to other bodies which resemble our own, so far as our direct experience goes, in passing continuously from place to place and undergoing only partial and gradual changes of form and quality. As we have existed-or, more exactly, as the body has been continuously presented-during the interval between two encounters with some other recognized body, so this is regarded as having continuously existed during its absence from us. However permanent we suppose the conscious subject to be, it is hard to see how, without the continuous presentation to it of such a group as the bodily self, we should ever be prompted to resolve the discontinuous presentations of external things into a continuity of existence. It might be said: Since the second presentation of a particular group would, by the mere workings of psychical laws, coalesce with the image of the first, this coalescence would suffice to “generate ” the concept of continued existence. But such assimilation is only the ground of an intellectual identification and furnishes no motive, one way or the other, for real identification: between a second presentation of A and the presentation at different times of two A's there is so far no difference. Real identity no more involves exact similarity than exact similarity involves sameness of things; on the contrary, we are wont to find the same thing alter with time, so that exact similarity after an interval, so far from suggesting one thing, is often the surest proof that there are two concerned. Of such real identity, then, it would seem we must have direct experience; and we have it in the continuous presentation of the bodily self; apart from this it could not be “ generated " by association among changing presentations. Other bodies being in the first instance personified, that then is regarded as one thing-from whatever point of View we look at it, whether as part of a larger thing or as itself compounded of such parts-which has had one beginning in time. But what is it that has thus a beginning and, continues indefinitely? This leads to our last point.
e. So far we have been concerned only with the combination of sensory and motor presentations into 'groups and with the differentiation of group from group; the relations to Substanti-
each other of the constituents of each group still, , m, , for the most part remain. To these relations in the main must be referred the correlative concepts of substance and attribute, the distinction in substances of qualities and powers, of primary qualities and secondary, and the like.1 Of all the constituents of things only one is universally present, that above described as physical solidity, which presents itself according to circumstances as impenetrability, resistance or weight. Things differing in temperature, colour, taste and smell agree in resisting compression, in filling space. Because of this quality we regard the wind as a thing, though it has neither shape nor colour, while a shadow, though it has both but not resistance, is the very type of nothingness. This constituent is invariable, while other qualities are either absent or change form altering, colour disappearing with light, sound and smells intermitting. Many of the other qualities-colour, temperature, sound, smell-increase in intensity if we advance till we touch a body occupying space; with the same movement too its visual magnitude varies. At the moment of contact an unvarying tactual magnitude is ascertained, while the other qualities and the visual magnitude reach a, fixed maximum; then first it becomes possible by effort to change or attempt to change the position and form of what we apprehend. This tangible plenum we thenceforth regard as the seat and source of all the qualities we project into it. In other words, that which occupies space is psychologically the substantial; the other real constituents are but its properties or attributes, the marks or manifestations which lead us to expect its presence.
Imagination or I deation?
21. Before the intuition of things has reached a stage so complete and definite as that just described, imagination or ideation as distinct from perception has well begun. In Impressions
passing to the consideration of this higher form of, ,, , d, deas mental life we must endeavour first of all analytically to distinguish the two as precisely as may be and then to trace the gradual development of the higher.
To begin, it is very questionable whether Hume was right in applying Locke's distinction of simple and complex to ideas in the narrower sense as well as to impressions. 'f That idea. of red, ” says Hume, “ which we form in the dark and that impression which strikes our eyes in the sunshine differ only in degree, not in nature.”3 But what he seems to have overlooked is that, whereas we may have a mere sensation red, we can only have an image or representation of a red thing or a red form, i.e of red-in some way ideally projected' or intuited. In other words, there are no ideas-though there are concepts-answering to simple or isolated impressions. The synthesis which has taken place in the evolution of the percept can o'nly partially fail in the idea, and never so far as to leave us with a chaotic “ manifold ” of mere sensational remnants. On the contrary, we ind that in “constructive imagination ” a new kind of effort is often requisite in order partially to dissociate these representational complexes as a preliminary to new combinations. But it is doubtful Whether the results of such an analysis are ever the ultimate elements of the percept, that is, merely isolated impressions in a fainter form. We may now try to ascertain further the characteristic marks which distinguish what is imaged from what is perceived.
might be more fully treated under the head of “ Thought and Conception.” Still, inasmuch as the material warrant for these concepts is contained more or less implicit in our percepts, some consideration of it is in place here.
2 ldeation-“ a word of my own coining, " says James Mill. 3 Treatise of Human Nature, bk. i. pt. i. § I. The distinction between the thing and its properties is one that