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knowledge and our practice, as if they had never existed at all. But when we are placed in some novel situation, or when, in particular, we are deprived of any one of the senses,
the pressure of our necessities creates that interest which was wanting before. Then we delay upon, and mark, and remember, and interpret a multitude of evancscent intimations which were formerly neglected. The senses thus acquire a very considerable relative power and value. And in order to make out a satisfactory explanation of some instances of habits, it is perhaps necessary that this relative increase should be added to the dilect and positive augmentation of vigour and quickness resulting from mere repetition or exercise.
$ 55. Of habits as modified by particular callings and arts. Hitherto it has been our chief object to examine habits in their relation to the senses separately; it is proper also to take a general view of them, as formed and modified by the particular callings and employments of men. Habits of perception are frequently formed under such circumstances, where all the senses are not only possessed, but where they exist with their ordinary aptitudes and powers.-In consequence of the habits which he has been called upon to form by his particular situation, a farmer of a tolerable degree of experience and discernment requires but a slight inspection, in order to give an opinion on the qualities of a piece of land, and its suitableness for a settlement. A skilful printer will at once notice everything of excellence or of deficiency in the mechanical execution of a printed work.—The same results are found in all who practise the fine arts. An experienced painter at once detects a mannerism in colouring, combinations and contrasts of light and shade, and peculiarities of form, proportion, or position, which infallibly escape a person of more limited experience.
Dr. Reid speaks on this subject in the following characteristic manner.—“Not only men, but children, idiots, and brutes, acquire by habit many perceptions which they had not originally. Almost every employment in life hath perceptions of this kind that are peculiar to it The shepherd knows every sheep of his flock, as we do our
acquaintance, and can pick them out of another flock one by one. The butcher knows by sight the weight and quality of his beeves and sheep before they are killed The fariner perceives by his eye very nearly the quantity of hay in a ick, or of corn in a heap. The sailor sees the burden, the built, and the distance of a ship at sea, while she is a great way
Every man accustomed to writing, distinguishes acquaintances by their handwriting, as he does by their faces. And the painter distinguishes, in the works of his art, the style of all the great masters. In a word, acquired perception is very different in different persons, according to the diversity of objects about which they are employed, and the application they bestow in observing them."* $ 56. The law of habit considered in reference to the perception of the
outlines and forms of objects. Before leaving the subject of Habit, considered as influencing Sensation and Perception, there is one other topic which seems to be entitled to a brief notice; we refer to the manner in which we perceive the outlines and forms of bodies. In discussing the subject of Attention, Mr. Stewart, in connexion with his views on that subject, introduces some remarks in respect to vision. He makes this supposition, That the eye is fixed in a particular position, and the picture of an object is painted on the retina. He then starts this inquiry: Does the mind perceive the complete figure of the object at once, or is this perception the result of the various perceptions we have of the different points in the outline ?-He holds the opinion, that the perception is the result of our perceptions of the different points in the outline, which he adopts as naturally consequent on such views, as the following The outline of every body is made up of points or smallest visible portions; no two of these points can be in precisely the same direction; therefore every point by itself constitutes just as distinct an object of attention to the mind, as if it were separated by some interval of empty space from all the other points. The conclusion therefore is, as every body is made up of parts, and as the perception 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.
* Reid's Inquiry into the Human Mind, chap. vi., o 20.
But if we adopt this view of Mr. Stewart, it is incumdent 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
$ 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. Whene ter 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. Additior.al illus.ra: 'ons of Mr. Stewarı 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 phil osophical 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 klowledge 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. 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.
The process li 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 ali 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.
9 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. fessing 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 bette understanding of their distinctive character if we mention more particularly how they differ both from sensations