There is a mere natural and mechanical use of the senses which strengthens the body without improving the judgment. It is all very well to swim, run, jump, whip a top, throw stones; but have we nothing but arms and legs? Have we not eyes and ears as well; and are not these organs necessary for the use of the rest? Do not merely exercise the strength, exercise all the senses by which it is guided; make the best use of every one of them, and check the results of one by the other. Measure, count, weigh, compare. Do not use force till you have estimated the resistance; let the estimation of the effect always precede the application of the means. Get the child interested in avoiding insufficient or superfluous efforts. If in this way you train him to calculate the effects of all his movements, and to correct his mistakes by experience, is it not clear that the more he does the wiser he will become? Take the case of moving a heavy mass; if he takes too long a lever, he will waste his strength; if it is too short, he will not have strength enough; experience will teach him to use the very stick he needs. This knowledge is not beyond his years. Take, for example, a load to be carried; if he wants to carry as much as he can, and not to take up more than he can carry, must he not calculate the weight by the appearance? Does he know how to compare masses of like substance and different size, or to choose between masses of the same size and different substances? He must set to work to compare their specific weights. I have seen a young man, very highly educated, who could not be convinced, till he had tried it, that a bucket full of blocks of oak weighed less than the same bucket full of water. All our senses are not equally under our control. One of them, touch, is always busy during our waking hours; it is spread over the whole surface of the body, like a sentinel ever on the watch to warn us of anything which may do us harm. Whether we will or not, we learn to use it first of all by experience, by constant practice, and therefore we have less need for special training for it. Yet we know that the blind have a surer and more delicate sense of touch than we, for not being guided by the one sense, they are forced to get from the touch what we get from sight. Why, then, are not we trained to walk as they do in the dark, to recognise what we touch, to distinguish things about us; in a word, to do at night and in the dark what they do in the daytime without sight? We are better off than they while the sun shines; in the dark it is their turn to be our guide. We are blind half our time, with this difference: the really blind always know what to do, while we are afraid to stir in the dark. We have lights, you say. What always artificial aids. Who can insure that they will always be at hand when required. I had rather Emil's eyes were in his finger tips, than in the chandler's shop.