Графични страници
PDF файл
ePub

attention we do not discover that the impression has been experienced by the instrumentality of any organ whatever. Hence the perceptions of the mind are always directed to the objects which make the impressions, and not to the instruments by means of which the impressions are experienced. The instruments perform their functions under Nature's care; and, as has been already observed, are not subject to the will. been distracted, not benefited, by a consciousness of their internal action, when they perform their functions. It is when they become diseased that we become conscious of their action, and then the consciousness is painful. Every one must be sensible of this fact, whose eyes or ears have been diseased.

We should have

Dr. Spurzheim observes, that "the brain seems to be necessary to every kind of perception, even to that of the immediate functions of the external senses; but it is not yet ascertained, though it is probable, that one fundamental power, inherent in a particular part of the brain, knows and conceives as sensations, all the varied impressions made on the external senses. Some phrenologists think that each external sense has a peculiar portion of brain for this end, and that the combined action of its nerve and of this cerebral part, is necessary to the accomplishment of its functions. That the nerve of taste and a portion of brain, for instance, are necessary to perceive savors; the olfactory nerve and a cerebral part, to distinguish odors, &c. I do not believe that consciousness happens without brain, but I see no reason to surmise that the immediate functions of each external sense require a particular portion of the brain, in order to be recognised as determinate sensations." (Dr. Spurzheim's Phrenology, p. 289.)

After these general considerations, which apply to all the external senses, a few words may be added on the specific functions of each sense in particular.

FEEDING OR TOUCH.

Dr. Spurzheim inferred, from pathological facts, that the nerves of motion must be distinct from the nerves of feeling; and subse

quent experiments have proved his inference to be well founded. This subject has been treated of on page 54. The sense of feeling is continued, not only over the whole external surface of the body, but even over the intestinal canal. It gives rise to the sensations of pain and pleasure; of the variations of temperature; and of dryness and moisture. These cannot be recalled by the will; and I therefore consider them as depending on the sense alone. The impressions made upon this sense serve as the means of exciting in the mind perceptions of figure, of roughness and smoothness, and numerous other classes of ideas; but the power of experiencing these perceptions, is in proportion to the perfection of certain internal faculties, and of the sense of touch jointly, and not in proportion to the perfection of this sense alone.

TASTE.

THE functions of this sense are, to produce sensations of taste alone; and these cannot be recalled by the will. We may judge of the qualities of external bodies, by means of the impressions made on this sense; but to form ideas of such qualities is the province of the internal faculties.

SMELL

By means of smell, the external world acts upon man and animals from a distance. Odorous particles are conveyed from bodies, and inform sentient beings of the existence of the substances from which they emanate. The functions of smell are confined to the producing of agreeable or disagreeable sensations, when the organ is so affected. These cannot be reproduced by an effort of the will. Various ideas are formed of the qualities of external bodies, by the impressions which they make upon this sense; but these ideas are formed by the internal faculties of the mind.

HEARING.

IN new-born children, this sense is not yet active; but it improves by degrees, and in proportion as the vigor of the organ increases. It is a very common opinion, that music, and the faculty of speech, are the result of the sense of hearing; but this notion is erroneous.

As already mentioned, the auditory apparatus being excited to activity by an external cause, produces only the impression of sound and here its functions terminate. If, besides, the faculty of Tune is possessed by any individual, melody in sounds is perceived by that faculty. If the faculty is not possessed, such perceptions cannot exist. Hence, among birds, the female hears as well as the male; and yet the song of the male is very much superior to that of the female. Among mankind, also, many individuals hear, and yet are insensible to melody. Thus, both in man and other animals, there is no proportion betwixt the perfection of hearing, and the perfection of the power of perceiving melody. If it were part of the functions of the auditory apparatus to give the perception of melody, how does it happen that, in one individual, the apparatus can perform only one-half of its functions, while in others it performs the whole? This is not like Nature's work. Finally, hearing cannot produce music; because the auditory apparatus is excited only by sounds, which are already produced. The first musician began to produce music before he had heard it; and he did so from an internal impulse given by a faculty of the mind. Singing-birds, moreover, which have been hatched by strange females, sing naturally, and without any instruction, the song of their species, as soon as their internal organization is active. Hence the males of every species preserve their natural song, though they have been brought up in the society of individuals of a different kind. Hence also musicians, who have lost

their hearing, continue to compose. They possess the internal faculty; and it being independent of the auditory apparatus, conceives the impressions which different sounds naturally produce

long after the ear has ceased to be capable of allowing these sounds to be experienced anew; hence, likewise, deaf and dumb persons have an innate sentiment of measure and cadence. Though, however, hearing does not produce music, yet, without an auditory apparatus, fitted to receive the impressions made by tones, melody could not be perceived; and, unless that apparatus had once been possessed, neither could melody be produced, because the individual could not judge of the impressions which the sounds he made were fitted to make upon those who hear.

It is a very common opinion also, that hearing alone, or hearing and voice jointly, produce the faculty of speech. This error will be refuted, by considering in what any language consists, and how every language is produced. Language has been divided into two kinds, natural and artificial. In both kinds, a certain sign is used to indicate to others certain feelings or ideas of the mind. Various motions of the body, and expressions of the countenance, indicate, the moment they are beheld, certain emotions and sentiments. In this case, the expression of the countenance, or the motion of the body, is a sign fitted by nature to excite in us the perception of the feeling. It is obvious, that the power of the sign, in this case, to excite the perception, does not depend either upon hearing or voice; for neither is employed in producing it but that the effect is an ultimate fact of our constitution, which must be referred to the will of our Creator. Besides these signs, however, we make use of many others to communicate our thoughts, which have no original connexion with the things signified. For example, the word TABLE has no necessary connexion with the thing upon which I now write. How, then, does the word come to indicate the thing? The internal faculties first conceive the object having done so, they wish to fix upon a sign by which that conception shall be always indicated again. They, therefore, employ the voice to make the sound which we express when we utter the word table. The thing itself being pointed out, and the sound being uttered at the same time, the meaning of it comes to be understood; and hence every time it is pronounced, the idea of the thing is suggested. But we are not to suppose that the auditory

apparatus, or the organs of voice, conceive the dea of the table. This was done by the internal faculties alone; and these merely made use of the organs of voice as instruments for producing a sign. Hence the reason why monkeys do not speak is, not because they want the sense of hearing, and organs of voice, but because they have not certain internal faculties, which fix upon signs to indicate the conceptions formed by the mind.

The proper function, then, of the sense of hearing, is confined to the production of the impressions which we call sounds; yet it assists a great number of internal faculties.

The auditory nerve has a more intimate connexion with the organs of the moral sentiments, than with those of the intellectual faculties.

SIGHT.

THIS fifth and last of the senses, is the second of those which inform man and other animals of remote objects, by means of an intermedium; and the intermedium, in this instance, is Light.

This sense has been said to acquire its functions by touch or by habit. Bishop Berkley is supposed by the metaphysicians to have discovered the true theory of vision, and the result of his investigation is, "that a man born blind, being made to see, would not at first have any idea of distance by sight. The sun and stars, the remotest objects as well as the nearest, would all seem to be in his eye, or rather in his mind."-Stewart's Dissert. p. ii. 109. Dr. Reid, and many other philosophers, have written ingenious disquisitions, to show that our perceptions of distance, figure, and motion, are acquired. "Philosophy," says Mr. James Mill, "has ascertained that we derive nothing from the eye whatever but sensations of color; that the idea of extension in which size, and form, and distance are included, is derived from sensations not in the eye, but in the muscular part of our frame. How then is it that we receive accurate information, by the eye, of size and shape, and distance? By association merely." Analysis of the Phenomena of the Human Mind, vol. i. chap. iii. p. 73. These speculations have proceeded on the principle, that Nature has done

« ПредишнаНапред »