Графични страници
PDF файл
ePub

ception of the figure of the whole object implies a knowledge of the relative situation of the different parts with respect to each other, that such perception is the result of a number of different acts of attention.

But if we adopt this view of Mr. Stewart, it is incumbent upon us to show how it happens that we appear to see the object at once. The various facts which have been brought forward in this chapter appear to furnish us with a solution of this question. The answer is, that the acts of perception are performed with such rapidity, that the effect with respect to us is the same as if it were instantaneous. A habit has been formed; the glance of the mind, in the highest exercise of that habit, is indescribably quick; time is virtually annihilated; and separate moments are to our apprehension of them crowded into one.

57. Notice of some facts which favour the above doctrine.

Some persons will probably entertain doubts of Mr. Stewart's explanation of the manner in which we perceive the outlines of objects; but there are various circumstances which tend to confirm it.-When we look for the first time on any object which is diversified with gaudy colours, the mind is evidently perplexed with the variety of perceptions which arise; the view is indistinct, which would not be the case if there were only one, and that an immediate perception. And even in paintings, which are of a more laudable execution, the effects at the first perception will be similar.

But there is another fact which comes still more directly to the present point. We find that we do not have as distinct an idea, at the first glance, of a figure of a hundred sides, as we do of a triangle or square. But we evidently should, if the perception of visible figure were the immediate consequence of the picture on the retina, and not the combined result of the separate perceptions of the points in the outline. Whenever the figure is very simple, the process of the mind is so very rapid that the perception seems to be instantaneous. But when the sides are multiplied beyond a certain number, the interval of time necessary for these different acts of attention

becomes perceptible. We are then distinctly conscious that the mind labours from one part of the object to another, and that some time elapses before we grasp it as a whole.

58. Additional illustrations of Mr. Stewart's doctrine. These views and illustrations are still further confirmed by some interesting, and perhaps more decisive facts. In 1807, Sir Everard Home, well known for his various philosophical publications, read before the Royal Society an account of two blind children whom he had couched for the cataract. One of these was John Salter. Upon this boy various experiments were made, for the purpose, among other things, of ascertaining whether the sense of sight does originally, and of itself alone, give us a knowledge of the true figure of bodies. Some of the facts elicited under these circumstances have a bearing upon the subject now before us. In repeated instances, on the day of his restoration to sight, the boy called square and triangular bodies, which were presented to the visual sense merely, round. On a square body being presented to him, he expressed a desire to touch it. "This being refused, he examined it for some time, and said at last that he had found a corner, and then readily counted the four corners of the square; and afterward, when a triangle was shown him, he counted the corners in the same way; but, in doing so, his eye went along the edge from corner to corner, naming them as he went along." On the thirteenth day after the cataract was removed, the visual power he had acquired was so small, that he could not by sight tell a square from a circle, without previously directing his sight to the corners of the square figure as he did at first, and thus passing from corner to corner, and counting them one by one. It was noticed that the sight seemed to labour slowly onward from one point and angle to another, as if it were incapable of embracing the outline by a simultaneous and undivided movement. The process, however, became more and more easy and rapid, until the perception, which at first was obviously made up of distinct and successive acts, came to be in appearance (and we may suppose it was only in appearance) a concentrated and single one.

It was the same with Caspar Hauser. It is remarked by his biographer, that whenever a person was introduced to him, (this was probably soon after his release from his prison,) he went up very close to him, regarded him with a sharp, staring look, and noticed particularly each distinct part of his face, such as the forehead, eyes, nose, mouth, and chin. He then collected and consolidated all the different parts of the countenance, which he had noticed separately and piece by piece, into one whole. And it was not till after this process that he seemed to have a knowledge of the countenance or face, in distinction from the parts of the face.

CHAPTER VIII.

CONCEPTIONS.

59. Meaning and characteristics of conceptions.

WE are now led, as we advance in the general subject of intellectual states of EXTERNAL ORIGIN, to contemplate the mind in another view, viz., as employed in giving rise to what are usually termed CONCEPTIONS. Without professing to propose a definition in all respects unexceptionable, we are entitled to say, in general terms, that this name is given to any re-existing sensations whatever which the mind has felt at some former period, and to the ideas which we frame of absent objects of perception. Whenever we have conceptions, our sensations and perceptions are replaced, as Shakspeare expresses it, in the "mind's eye," without our at all considering at what time or in what place they first originated. In other words, they are revived or recalled, and nothing more.— Using, therefore, the term CONCEPTIONS to express a class of mental states, and, in accordance with the general plan, having particular reference in our remarks here to such as are of external origin, it may aid in the better understanding of their distinctive character if we mention more particularly how they differ both from sensations G

and perceptions, and also from remembrances, with which last some may imagine them to be essentially the same.

(I.) Conceptions differ from the ordinary sensations and perceptions in this respect, that both their causes and their objects are absent. When the rose, the honeysuckle, or other odoriferous body is presented to us, the effect which follows in the mind is termed a sensation. When we afterward think of that sensation, (as we sometimes express it,) when the sensation is recalled, even though very imperfectly, without the object which originally caused it being present, it then becomes, by the use of language, a CONCEPTION. And it is the same in any instance of perception. When, in strictness of speech, we are said to perceive anything, as a tree, a building, or a mountain, the objects of our perceptions are in all cases before us. But we may form conceptions of them; they may be recalled and exist in the mind's eye, however remote they may be in fact, both in time and place.

(II.) They differ also from remembrances or ideas of memory. We take no account of the period when those objects which laid the foundation of them were present; whereas, in every act of the memory, there is combined with the conception a notion of the past. Hence, as those states of mind, which we call conceptions, possess these distinctive marks, they are well entitled to a sep

arate name.

CONCEPTIONS are regulated in their appearance and disappearance by the principles of Association, which will be explained hereafter. Whenever at any time we may use the phrase "power of conception" or "faculty of conception," nothing more is to be understood by such expressions than this, that there is in the mind a susceptibility of feelings or ideas possessing the marks which we have ascribed to this class.

60. Of conceptions of objects of sight.

One of the striking facts in regard to our conceptions is, that we can far more easily conceive of the objects of some senses than of others. He who has visited the Pyramids of Egypt and the imposing remains of Grecian temples, or has beheld, among nature's still greater works,

the towering heights of the Alps and the mighty cataract of Niagara, will never afterward be at a loss in forming a vivid conception of those interesting objects. The visual perceptions are so easily and so distinctly recalled, that it is hardly too much to say of them, that they seem to exist as permanent pictures in the mind. It is related of Carsten Niebuhr, a well-known traveller in the East, that, in extreme old age, after he had become blind, he entertained his visiters with interesting details of what he had seen many years before at Persepolis; describing the walls on which the inscriptions and bas-reliefs of which he spoke were found, just as one would describe a building which he had recently visited. His son, who has given an account of his life, remarks, in connexion with this fact: "We could not conceal our astonishment. He said to us, that, as he lay blind upon his bed, the images of all that he had seen in the East were ever present to his soul; and it was therefore no wonder that he should speak of them as of yesterday. In like manner, there was vividly reflected to him, in the hours of stillness, the nocturnal view of the deep Asiatic heavens, with their brilliant host of stars, which he had so often contemplated; or else their blue and lofty vault by day; and this was his greatest enjoyment."

There seems to be less vividness in the conceptions of sound, touch, taste, and smell; particularly the last three. Every one knows that it is difficult in ordinary cases to recall with much distinctness a particular pain which we have formerly experienced, or a particular taste, or smell. The fact that the perceptions of sight are more easily and distinctly recalled than others, may be thus partially explained. Visible objects, or, rather, the outlines of them, are complex; that is, they are made up of a great number of points or very small portions. Hence the conception which we form of such an object as a whole, is aided by the principles of association. The reason is obvious. As every original perception of a visible object is a compound made up of many parts, whenever we subsequently have a conception of it, the process is the same; we have a conception of a part of the object, and the principles of association help us in conceiving of the

« ПредишнаНапред »