Émile; Or, Concerning Education; Extracts

by Jean-Jacques Rousseau

Although, of all our senses, touch is the one most constantly used, still, as I have said, its conclusions are the most rude and imperfect. This is because it is always used at the same time with sight; and because the eye attains its object sooner than the hand; the mind nearly always decides without appealing to touch. On the other hand, the decisions of touch, just because they are so limited in their range, are the most accurate. For as they extend no farther than our arm's length, they correct the errors of other senses, which deal with distant objects, and scarcely grasp these objects at all, whereas all that the touch perceives it perceives thoroughly. Besides, if to nerve-force we add muscular action, we form a simultaneous impression, and judge of weight and solidity as well as of temperature, size, and shape. Thus touch, which of all our senses best informs us concerning impressions made upon us by external things, is the one oftenest used, and gives us most directly the knowledge necessary to our preservation.

The Sense of Sight.

The sense of touch confines its operations to a very narrow sphere around us, but those of sight extend far beyond; this sense is therefore liable to be mistaken. With a single glance a man takes in half his own horizon, and in these myriad impressions, and judgments resulting from them, how is it credible that there should be no mistakes? Sight, therefore, is the most defective of all our senses, precisely because it is most far-reaching, and because its operations, by far preceding all others, are too immediate and too vast to receive correction from them. Besides, the very illusions of perspective are needed to make us understand extension, and to help us in comparing its parts. If there were no false appearances, we could see nothing at a distance; if there were no gradations in size, we could form no estimate of distance, or rather there would be no distance at all. If of two trees the one a hundred paces away seemed as large and distinct as the other, ten paces distant, we should place them side by side. If we saw all objects in their true dimensions, we should see no space whatever; everything would appear to be directly beneath our eye.

For judging of the size and distance of objects, sight has only one measure, and that is the angle they form with our eye. As this is the simple effect of a compound cause, the judgment we form from it leaves each particular case undecided or is necessarily imperfect. For how can I by the sight alone tell whether the angle which makes one object appear smaller than another is caused by the really lesser magnitude of the object or by its greater distance from me?

An opposite method must therefore be pursued. Instead of relying on one sensation only, we must repeat it, verify it by others, subordinate sight to touch, repressing the impetuosity of the first by the steady, even pace of the second. For lack of this caution we measure very inaccurately by the eye, in determining height, length, depth, and distance. That this is not due to organic defect, but to careless use, is proved by the fact that engineers, surveyors, architects, masons, and painters generally have a far more accurate eye than we, and estimate measures of extension more correctly. Their business gives them experience that we neglect to acquire, and thus they correct the ambiguity of the angle by means of appearances associated with it, which enable them to determine more exactly the relation of the two things producing the angle.

Children are easily led into anything that allows unconstrained movement of the body. There are a thousand ways of interesting them in measuring, discovering, and estimating distances. "Yonder is a very tall cherry-tree; how can we manage to get some cherries? Will the ladder in the barn do? There is a very wide brook; how can we cross it? Would one of the planks in the yard be long enough? We want to throw a line from our windows and catch some fish in the moat around the house; how many fathoms long ought the line to be? I want to put up a swing between those two trees; would four yards of rope be enough for it? They say that in the other house our room will be twenty-five feet square; do you think that will suit us? Will it be larger than this? We are very hungry; which of those two villages yonder can we reach soonest, and have our dinner?"

As the sense of sight is the one least easily separated from the judgments of the mind, we need a great deal of time for learning how to see. We must for a long time compare sight with touch, if we would accustom our eye to report forms and distances accurately.

Without touch and without progressive movement, the keenest eye-sight in the world could give us no idea of extent. To an oyster the entire universe must be only a single point. Only by walking, feeling, counting, and measuring, do we learn to estimate distances.

If we always measure them, however, our eye, depending on this, will never gain accuracy. Yet the child ought not to pass too soon from measuring to estimating. It will be better for him, after comparing by parts what he cannot compare as wholes, finally to substitute for measured aliquot parts others, obtained by the eye alone. He should train himself in this manner of measuring instead of always measuring with the hand. I prefer that the very first operations of this kind should be verified by actual measurements, so that he may correct the mistakes arising from false appearances by a better judgment. There are natural measures, nearly the same everywhere, such as a man's pace, the length of his arm, or his height. When the child is calculating the height of the story of a house, his tutor may serve as a unit of measure. In estimating the altitude of a steeple, he may compare it with that of the neighboring houses. If he wants to know how many leagues there are in a given journey, let him reckon the number of hours spent in making it on foot. And by all means do none of this work for him; let him do it himself.

We cannot learn to judge correctly of the extent and size of bodies without also learning to recognize their forms, and even to imitate them. For such imitation is absolutely dependent on the laws of perspective, and we cannot estimate extent from appearances without some appreciation of these laws.