I have known people who tried to train the children not to fear the dark by startling them. This is a very bad plan; its effects are just the opposite of those desired, and it only makes children more timid. Neither reason nor habit can secure us from the fear of a present danger whose degree and kind are unknown, nor from the fear of surprises which we have often experienced. Yet how will you make sure that you can preserve your pupil from such accidents? I consider this the best advice to give him beforehand. I should say to Emile, "This is a matter of self-defence, for the aggressor does not let you know whether he means to hurt or frighten you, and as the advantage is on his side you cannot even take refuge in flight. Therefore seize boldly anything, whether man or beast, which takes you unawares in the dark. Grasp it, squeeze it with all your might; if it struggles, strike, and do not spare your blows; and whatever he may say or do, do not let him go till you know just who he is. The event will probably prove that you had little to be afraid of, but this way of treating practical jokers would naturally prevent their trying it again." Although touch is the sense oftenest used, its discrimination remains, as I have already pointed out, coarser and more imperfect than that of any other sense, because we always use sight along with it; the eye perceives the thing first, and the mind almost always judges without the hand. On the other hand, discrimination by touch is the surest just because of its limitations; for extending only as far as our hands can reach, it corrects the hasty judgments of the other senses, which pounce upon objects scarcely perceived, while what we learn by touch is learnt thoroughly. Moreover, touch, when required, unites the force of our muscles to the action of the nerves; we associate by simultaneous sensations our ideas of temperature, size, and shape, to those of weight and density. Thus touch is the sense which best teaches us the action of foreign bodies upon ourselves, the sense which most directly supplies us with the knowledge required for self-preservation. As the trained touch takes the place of sight, why should it not, to some extent, take the place of hearing, since sounds set up, in sonorous bodies, vibrations perceptible by touch? By placing the hand on the body of a 'cello one can distinguish without the use of eye or ear, merely by the way in which the wood vibrates and trembles, whether the sound given out is sharp or flat, whether it is drawn from the treble string or the bass. If our touch were trained to note these differences, no doubt we might in time become so sensitive as to hear a whole tune by means of our fingers. But if we admit this, it is clear that one could easily speak to the deaf by means of music; for tone and measure are no less capable of regular combination than voice and articulation, so that they might be used as the elements of speech.