however most illogical to appeal to these results in order to discredit the genetic or empirical theory of visual perception which alone accounts for them1.

Intuition of Things.

§ 6. We come now to the intuition of things or, as it is more often called, 'the perception of the external world.' In a complex percept, such as that of an orange or a piece of wax, may be distinguished the following items concerning which psychology may be expected to give an account: (a) the object's reality, (b) its solidity or occupation of space, (c) its unity and complexity, (d) its permanence, or rather its continuity in time and (e) its substantiality and the connexion of its attributes and powers. Though, in fact, these items are most intimately blended, our exposition will be clearer if we consider each for a moment apart.

a. The terms actuality and reality have each more than one meaning. Thus what is real, in the sense of material, is opposed to what is mental; as the existent or actual it is opposed to the non-existent; and again, what is actual is distinguished from what is merely possible. But here, by real or actual is meant, with a certain shade of difference-in so far as actual is more appropriate to movements and events-whatever is sense-given or presented in antithesis to whatever is ideal or represented. This seems at least their primary psychological meaning it is, at any rate, the one most in vogue in English philosophy, over-tinged as that is with psychology. Any words there are psychological factors present: as v. Kries puts it, the observer has to understand the object, and for this a very noticeable time is often requisite. Cf. Helmholtz's Phys. Optik, 3rd ed. 1911, III. p. 470.

Nevertheless, if that theory is to work it must accept extensity as an ultimate fact. To overlook this was Helmholtz's initial mistake and to recognise it Hering's great merit. Unhappily he-like William James-goes too far in the opposite extreme. He attributes a length, breadth and depth value to each retinal point as such, in fact treats space as perceptually on a par with light, heat or sound. Such a position is psychologically indefensible. Without localisation, as we have already said, we have not space but only extensity: with localisation we have not only extensity but relations that imply movement and are only brought to our knowledge by means of it. See the very able criticism by von Kries, op. cit. pp. 522-34.

2 Thus Locke says, "Our simple ideas [i.e. presentations or impressions, as we should now say] are all real...and not fictions at pleasure; for the mind...can make to itself no simple idea more than what it has received" (Essay, ii. 30, 2). And Berkeley says, "The ideas imprinted on the senses by the Author of Nature are called real

W. P.

II

examination of this characteristic will be best deferred till we come to deal with ideation generally'. Meanwhile it will suffice to shew that reality or actuality is not a single distinct element added to the others which enter into the complex presentation of what we call a thing, as colour or solidity may be. Nor is it a special relation among these elements, like that of substance and attribute, for example. For in both these respects the real and the ideal, the actual and the possible, are alike. All the elements or qualities within the complex, and all the relations of those elements to each other, are the same in the rose represented as in the presented rose. The difference turns, not upon what these elements are, regarded as qualities or relations whether presented or represented: it turns solely upon whatever it is that distinguishes the presentation from the representation of the thing's qualities or their relations. Now this distinction, as we shall presently see, depends partly upon the relation of the presentation of the thing to other presentations in consciousness with it', partly upon the relation to it, the attitude (Einstellung) which it evokes in the subject whose presentation it is. In these respects we find a difference, not only between the simple qualities, such as cold, hard, and sweet in strawberry ice, e.g., as presented and as represented; but also, though less conspicuously, in the spatial, and even the temporal, relations which enter into our intuition as distinct from our imagination of it. So then, reality or actuality is not strictly an item by itself, but a characteristic of all the items that follow. Epistemologically expressed it answers to the existential judgment: It is or There is, and a judgment of this kind all perception implies.

b. In the so-called physical solidity or impenetrability of things our properly dynamic presentations or 'feelings of effort' come specially into play. They are not entirely absent in those movements of exploration by which we attain a knowledge of space. But it is when these movements are definitely resisted, or are only possible by increased effort, that we reach the full meaning of body as that which occupies space. What we come to call heat and cold, light and sound, the natural man regards

things; and those excited in the imagination, being less regular, vivid and constant, are more properly termed ideas or images of things, which they copy or represent (Prin. of Hum. Know. pt. i. § 33). 3 Cf. above, ch. v, § 8, p. 137.

1 See next chapter, § 1. 2 Cf. below, p. 173.

as real; and by and by he perhaps regards them as due to certain 'powers' of things, known or unknown. But he does not regard them as themselves things. At the outset things for him are all corporeal like his own body, the first and archetypal thing; and they are clearly intuited only when active touch is accomplished with effort. At a later stage passive touch without such effort may suffice, but only because pressures, depending on a subjective initiative, i.e. on voluntary muscular exertion, have been previously experienced. It is of more than psychological interest to remark that the primordial factor in external reality or 'materiality,' as we may now call it, is thus due to the projection of a subjectively determined exertion which meets with resistance, thereby making us acquainted with the occupation of space-autantitypy as it has been called1.

It is further of interest to remark that to yield such acquaintance the passive displacement of our own body by another would not suffice that alone would only be a new case of incopresentability: active resistance is essential to the nature of an opponent. Still we must remember that the accompanying senseimpressions are also an essential condition. Muscular effort without simultaneous sensations of contact would not yield the distinct presentation of something resistant occupying the space from which we have been obtruded and to which we would return. Nay more, it is in the highest degree an essential circumstance in this experience that the muscular effort, though subjectively initiated, is still only possible when there is contact with something that, as it seems, is making an effort the counterpart of our own. Especially important is the case where this counterpart effort also is our own, as when we press the hands together or pull with one against the other-" an experience," as Herbert Spencer has truly said, "which, perhaps more than any other, aids in developing the consciousness of objective power." But the 'something' is otherwise, so far, no more than thing-stuff: without the factors here already implied and now to be considered in more detail our psychological individual would fall short of distinct intuition of other things.

c. Of these remaining factors concerned in the intuition or perception of external things we have first of all to note the

1 Cf. Hamilton, ed. of Reid's Works, p. 847.

2 Principles of Psychology, 2nd ed. ii. § 468, p. 483.

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temporal and spatial relations of the sense-data composing them. Such relations are themselves in no way psychologically determined they are primarily and in the main quite independent of the subject's interest or of any psychological principles of synthesis or association whatsoever. But it is essential that impressions should recur, and recur more or less as they have previously occurred, if knowledge is ever to begin; for out of a continual chaos of sensation, all matter and no form, such as some philosophers describe, nothing but chaos could result. Even a flux of impressions having this real or sense-given order will not suffice; there must be also attention to, and retention of, the order itself as well. These indispensable processes at least are psychological.

But for its familiarity we should marvel at the fact that out of the variety of impressions simultaneously presented we do not instantly group together all the sounds and all the colours, all the touches and all the smells. But, dividing what is given together, we single out a certain sound or smell and regard that along with a certain colour and feel, similarly singled out, as belonging 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 projection would avail but little-indeed could hardly ariseunless the constituent impressions were again and again repeated in like order, so as to prompt anew the same grouping; nor 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, and 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 to be—in generalindependent of changes of position among them, that such complexes can become distinct unities, a world of many 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 from one point of view is 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 fixed. Our own body is both constant as a group and a constant item in every field of groups; and not 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 permanence 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 recognised body, so this comes to be 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 convert 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 a qualitative 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