NOTION OF EXTENDED MATTER. 369 we are conscious as one out of another, afford a condition of apprehending extension, seems to me to imply and take for granted the point in dispute: for I do not see how one sensation can be felt as out of another, without already supposing that we have a feeling of space. If I see two distinct objects before me, as two candle flames, I apprehend them as different objects, and as distant from one another by an interval of space; but this apprehension presupposes an independent experience and knowledge of lineal extension. There is no evidence to show that at the first sight of these objects, and before any association is formed between visible appearances and other movements, that I should be able to apprehend in the double appearance a difference of place. I feel a distinctness of impression, undoubtedly, partly optical and partly muscular, but in order that this distinctness may mean to me a difference of position in space, it must reveal the additional fact, that a certain movement of my arm would carry my hand from the one flame to the other, or that some other movement of mine would change by a definite amount the appearance I now see. If no information is conveyed respecting the possibility of movements of the body generally, no idea of is given, for we never consider that we have a notion of space unless we distinctly recognise this possibility. But how a vision to the eye can reveal beforehand what would be the experience of the hand or the other moving members, I am unable to see. space The conjoint experience of the senses and the movements appears to me to furnish all that we possess in the notion of extended matter. The association between sight and locomotion, or between touch and the movements of the arm, tells us that a given appearance implies the possibility of a certain. movement; that a remote building implies a certain continuance of our walking exertions to change its appearance into another that we call a near view; and the power of motion, the scope for moving, exhausts every property in the idea of space. We estimate it first by our own movements, and next by other movements measured in the first instance by our own, as, for example, the flight of a bird, the speed of BB a cannon ball, or the movement of light. The mental conception that we have of empty space is scope for movement, the possibility or potentiality of moving; and this conception we derive from our experience of movements. The resistance to movement is our notion of a plenum or occupied space; the extent of movement is our measure of the linear extension of body or extended magnitude. No internal revelation, nothing in the nature of intuition or innate conception, is required for giving us such notions as we actually have of these qualities. Perception and Belief of the Material World. 38. Inasmuch as knowledge and perception inhere in mind alone, it has been asked whether there be anything else than mind and its activities in the universe; or what reason have we for believing in the existence of counterpart objects apart from, and independent of, our sensations. May not waking thought be itself a dream? Or the problem may be illustrated thus: Baron Reichenbach has found a number of persons who see sparks and flames issuing from magnets; and it is disputed whether these are actual influences emanating from the magnetic bars, as much as their colour, lustre, weight, hardness, &c., or only phantasies of an excitable imagination. Such is the character of the controversy concerning the external and independent existence of the entire material world.* On this question the following remarks are submitted. (1.) There is no possible knowledge of the world except in reference to our minds. Knowledge means a state of mind; the notion of material things is a mental thing. We are incapable of discussing the existence of an independent mate *See in the Letters on the Philosophy of the Human Mind, by SAMUEL BAILEY, just published, an able exposure of the equivocations of language and confusion of ideas that have clouded the question relating to the perception of an external world. I quote a single sentence, giving a summary view of the position taken up by Mr. Bailey. It seems to have been only after a thousand struggles that the simple truth was arrived at, which is not by any means yet universally received, the truth that the perception of external things through the organs of sense is a direct mental act or phenomenon of consciousness not susceptible of being resolved into anything else.'-p. 111. EXTERNALITY IMPLIES OUR OWN ENERGY. 371 rial world; the very act is a contradiction. We can speak only of a world presented to our own minds. By an illusion of language, we fancy that we are capable of contemplating a world which does not enter into our own mental existence; but the attempt belies itself, for this contemplation is an effort of mind. (2.) Solidity, extension, and space, the foundation properties of the material world,-mean, as has been said above, certain movements and energies of our own body, and exist in our minds in the shape of feelings of force allied with visible, and tactile, and other sensible impressions. The sense of the external is the consciousness of particular energies and activities of our own. If we were the subjects of purely passive sensation,—such sensations as warmth, odour, light,-apart from any movement of any active member whatever, our recognition of the external world might be something very different from what we now experience. The state of the consciousness would then, so far as we are able to imagine it, be of the nature of a dream, and our perception of the universe would be sufficiently represented by a theory of idealism. But in us sensation is never wholly passive, and in general is much the reverse. Moreover, the tendency to movement exists before the stimulus of sensation; and movement gives a new character to our whole percipient existence. The putting forth of energy, and the consciousness of that energy, are distinct and characteristic facts totally different in their nature from pure sensation; meaning thereby sensation without activity, of which we can form some approximate idea from the extreme instances occurring to us of impressions languidly received. It is in this exercise of force that we must look for the peculiar feeling of externality of objects, or the distinction that we make between what impresses us from without and impressions not recognised as outward. Any impression that rouses a stroke of energy within us, and that varies exactly according as that energy varies, we call an outward impression. Dr. Johnson refuted Berkeley, as he thought, by kicking a stone. In fact, this view of Johnson's illustrates the real nature of our recognition of externality. It was his own action with its consequences, and not the optical impression of a stone on the eye, that satisfied him as to the existence of something outward. The sum total of all the occasions for putting forth active energy, or for conceiving this as possible to be put forth, is our external world. Taking the order of the senses followed in our exposition in the previous book, Touch is the first that decidedly makes us cognizant of an external world. But if we were confining ourselves to the class of sensations of soft touch, where we have the passive pleasure of the sense in highest perfection, we should not find much superiority in this sense over smell in the matter now under consideration. It is hard contact that suggests externality; and the reason is that in this contact we put forth force of our own. The more intense the pressure, the more energetic the activity called forth by it. This mixed state produced through reacting upon a sensation of touch by a muscular exertion, constitutes what is called the sense of resistance, a feeling which is the principal foundation of our notion of externality. There is no feeling of our nature of more importance to us, than that of resistance. Of all our sensations, it is the most unintermitted; for, whether we sit, or lie, or stand, or walk, still the feeling of resistance is present to us. Everything we touch at the same time resists; and everything we hear, see, taste, or smell, suggests the idea of something that resists. It is through the medium of resistance that every act, by which we subject to our use the objects and laws of nature, is performed. And, of the complex states of consciousness, there is hardly one in which the feeling or idea of resistance is not included.'* In fact we constantly carry about with us the feeling or the notion of resisting, in other words, the state where a sensation of touch is coupled with the putting forth of effort or force. (3) We experience certain uniformly recurring sensations, *MILL'S Analysis of the Human Mind, vol. i. p. 47. COINCIDENCE OF SENSATIONS WITH MOVEMENTS. 373 and certain uniform changes in these, when we exert particular energies. Thus the visible picture of our dwelling is a permanent and habitual experience, and the variations it is subject to, correspond principally to our own conscious movements. But at times the appearance is entirely withdrawn, and exists only in memory or idea. We then feel the difference between the two experiences, the ideal and the actual, and we assign some superiority in the mode of existence of the one over the other. The superiority we soon find to connect itself with the changes due to our movements; a mere picture or idea remains the same whatever be our bodily position or bodily exertions; the sensation that we call the actual is entirely at the mercy of our movements, shifting in every possible way according to the varieties of action that we go through. With a forward movement the visible impression enlarges, with a backward movement it diminishes. A movement of the eye shuts it off, another movement restores it. The carriage of the head alters it from side to side; the bending of the body varies it in other ways. We are constrained to make a distinction between the things that are thus shifted by all our movements, and the ideas or dreams that vary of themselves while we are still. Even if sensation were only in ourselves, we should still have to distinguish between present sensation and remembered or revived sensation; the reference of the one to our voluntary movements, and of the other to no such modifying causes, would oblige us to note a vital difference in the two classes of facts. Such is the uniformity of connexion between certain appearances and certain movements, that we come to anticipate the one through the other. We know that in some one position, as when lying in bed, a movement of the limbs will bring us to the sensation of a solid contact in the feet; that another series of movements will bring on a particular view to the sight; that a third movement will bring the sound of a bell to the ear, and so forth. We recognise all those sensible effects, thus brought uniformly into play by a regular series of waking voluntary actions, as totally different from our ideas, recollections, and dreams. (4) As our belief in the externality of the causes of our |