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Page:Popular Science Monthly Volume 65.djvu/237

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233
WHY IS THE HUMAN EAR IMMOBILE?

of these sensations stationary? Suppose the eye were to be trained to give special attention to the changes in objects before it, it would be essential that it should be prevented from making its usual excursions round the field open to it, and should be kept looking fixedly at one object. Not that this fixedness involves of necessity the inability to perceive a multiplicity of coexisting objects; it is found by experiment that when the eye is perfectly steady any one of the many points exposed to it can be attended to; and moreover, the attention can be directed from point to point. In hearing, too, we know that we can while remaining motionless, listen first to the sound from one quarter, then to that from another. But this only shows that when the natural instruments for performing certain acts are withdrawn from us, we may make shift to supply their places. We can see an object with the periphery of the eye, but we can not see it so well as when we freely turn the fovea upon it. And though we can direct our listening power from one point of the compass to another it remains true that the ear, smitten with immobility, can best fulfil its perceptive function when there is attention to the successive stimulations forming from one object.

It may seem that we have forgotten that such a sense as smell has an immobile organ, yet does not yield any special perception of succession. It is to be noted, however, that this sense is little developed in its perceptive aspect. We can not get the large number of discrete sensations from this sense that we can from hearing. We may by the ear distinguish five hundred sounds in the second. There is nothing in smell comparable to this. We need not wait to consider whether in its own undeveloped way smell does not after all remotely resemble hearing in the kind of perception it yields.

But we have not yet indicated the special forms assumed by the succession of sounds which it is so important to perceive. They are two—language and music. Language consists of a succession of sounds. When we consider how largely the intellectual life depends on language, we can see the enormous advantage of the development of the faculty of perceiving successive rather than simultaneous sounds. As every one is familiar with the importance of language, the greatness of the gain needs no further emphasis. Of less importance, though its significance for primeval man may yet prove to have been very great, is the appreciation of music. The music that is referred to is that given in melody. There is, apart from the melody, an appeal of each note and complex of notes which does not mean succession at all. Much of the thrill of music is an immediate effect of the individual note. But the appreciation of melody depends on the perception of succession. The eye is appealed to by a spatial combination of colors, the ear by a series of sounds. Headers of Lessing's Laocoon know how