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were neither sound, nor smell, nor taste, nor feeling; an operation had been performed upon his eye by which his attention was directed to that organ, as well as by the previous conversations which he must have had respecting his blindness, which induced him to submit to the operation. Had it not been for all this amount of previous experience, he probably would not have traced the sensations to his eye rather than to any other part of his body. In all similar operations that have been performed, by which persons capable of describing their sensations have first received the power of seeing, it has been found that the magnitude, distance, figure, and position of objects were all to be learned like a new language; and that when objects of different forms, as a cube and a sphere, were first seen by one who was previously acquainted with them, they could not be distinguished, by their appearance to the eye, so that the one could with certainty be said to be the cube and the other the sphere. Infants have, for a considerable time, no conception of the relative distance of objects. They stretch out their hands to touch or lay hold of the moon as readily as any other shining object that is near them. To a mind, therefore, circumstanced according to our hypothesis-connected with a body destitute of all power of motion-the various objects of sight presented to the eye would merely be like those visions of visible objects that seem to float before the eye when it is closed after tooking steadfastly at them; but instead of viewing them as floating before the eye, which is a notion that we derive from our habit of regarding all sensations as coming from without, it would conceive of them, as those floating visions in fact are, as only in the mind itself, without any separate existence from it.*
But if we could derive no knowledge of external objects from the sense of sight, much less could we derive such knowledge from the sense of hearing, or
*See Note A. in the Appendix.
tasting, or smelling; for even with all our experience, these senses give no notice of external bodies, of their direction, or distance, or form, nor even of their existence, except in consequence of our habit of tracing all sensations to some external cause. A mind circumstanced as we have supposed would be affected by different sounds, smells, tastes, merely as if they arose in the mind itself, without suggesting any cause.
It has been supposed by many of the latest and most enlightened writers on the mind, that we derive our knowledge of external objects from the sense of touch. That, however, to a mind in the condition supposed, seems to be impossible. No variety of tactile sensations, affecting the cheek or any part of the head, the touching or pressing any part with a blunt or a pointed instrument, rubbing it with a smooth or a rough surface, or the introduction to it of a cold or a heated atmosphere, could convey to it any conception of material substance acting upon it. These various modifications of feeling would appear to arise in the mind like the sensations derived from sounds or odours, without suggesting any external cause. Even with all our experience, we could not distinguish a puncture or cut with a sharp instrument from a touch of fire, or a drop of scalding water, or a touch of caustic. Our internal feelings of pain give us no intimation of the cause of it. We learn to judge of external objects by the modifications of the sense of touch, just as we learn to judge of them by the modifications of the sense of sight; but neither the one sense nor the other, nor both combined, would convey to us any notion or knowledge of objects external to the mind itself. The manner in which we obtain the notion of the external world, we shall endeavour to trace in a subsequent part of our investigation.
The second of the two important observations to which we have particularly called the attention of the reader is
8. That none of these sensations, nor any succession of them, could convey to the mind the notion of cause and effect. It has been argued that every change in the state of the mind necessarily suggests some cause of that change, at least that there must be such a cause. It is true that, having previously obtained possession of the notion of cause and effect, we do naturally ascribe every change to some cause. But in a mind circumstanced according to our hypothesis, we do not see how such a notion could be obtained. It is manifest that it could not ascribe the changes taking place within itself to any cause external to itself, for it has not acquired the notion of anything beyond itself. If, therefore, the idea of cause could arise in it, it could only be a cause within itself. Yet it could not regard a previous sensation as the cause of the following one, for that would be contrary to truth. Whether the revival of sensations in memory (to be treated of immediately) would suggest the idea of the original sensation being the cause of the remembrance of it; or whether a sensation or thought suggesting another thought might introduce the notion. of its being the cause of that other thought, might appear more doubtful; but without arguing the point, we only express our conviction, that the notion of cause and effect is obtained in another way, to be afterwards explained. In the meantime we proceed to consider the attainments which a human mind might make, circumstanced according to our hypothesis, open to influences from without, through the organs of sense, but destitute of power to move any muscle of the body.
Ir the various sensations that affect the mind were, on their ceasing, to pass away for ever, leaving no trace behind, the mind would be somewhat like a mirror with various objects passing before it, each producing its transient effect, and then vanishing: or like a musical instrument on which a tune has been played, which retains no trace of the tune, nor any peculiar aptitude for repeating that tune. But the mind is unlike the mirror or the musical instrument in this, that sensations which it has once experienced may be recalled to it without the intervention of the external object which originally awakened them. The mind is so constituted, that it may experience again, but with some modifications, the sensations of light and colour which it once experienced, without the help of the same external objects to reproduce those sensations; and may hear again, with certain modifications, the tune which it has once heard, without the help of the instrument, or of the musician who performed upon it.
Some metaphysicians confine the word memory to those instances of recal or representation of any sensation to the mind, in which it remembers along with it the time and circumstances in which it originally experienced the revived sensation, or at least is conscious that it did experience it. But surely if a sensation be recalled, it does not make any difference in that power of the mind which recalled it, that we remember, or do not remember, when and how we originally experienced it. We shall have occasion to return to this topic.
Thus, if the toll of a bell be heard, another toll of the same bell some time afterwards will recal to the mind the former toll; or if a bright light be once seen,
a second sensation afterwards, caused by a bright light, will recal the former; and so with regard to sensations received through any of the senses.
Nor is this power in one sensation to recal another confined to sensations of the same organ recalling one another. Sensations of sight may recal sensations of sound, or sensations of sound may recal sensations of sight; and so of all the senses, the sensations of which may reciprocally recal one another.
Neither is this power confined to sensations recalling sensations similar in any respect to one another. gentle sensation may recal a violent one; a long continued one may recal a transient one, or the contrary. Nay, the very dissimilarity of sensations may be the means of recalling one another.
Again, sensations that are experienced at the same time, or in immediate succession, naturally recal one another. If a mind in the condition which we have supposed were open to the vicissitudes of day and night, and if, immediately before daybreak, the sound of a drum were heard, then the sound of the drum would certainly recal the sensation of light formerly caused by the daybreak. Or, if immediately before the setting in of darkness the sound of a bell were heard, the sound of the same bell would certainly recal the sensation of darkness.
If, during the day, artificial darkness were produced, it would recal the sound of the bell which on former occasions had preceded darkness; and if, during the night, artificial light were introduced, it would recal the sound of the drum by which, on former occasions, the sensation of light had been preceded.
If bright light were generally accompanied with heat or warmth, then bright light would recal the sensation of warmth, and warmth the sensation of bright light. Or, if a particular smell and taste were experienced together, either of these sensations would recal the