2 3 2 POPULAR SCIENCE MONTHLY. 



of distinct quality takes its place; thus by its very nature sound lends 

 itself easily to this kind of perception. And when we listen to a 

 sounding object, our interest is in catching the sounds which come in 

 sequence. This is illustrated most distinctly, as we shall see, in atten- 

 tion to discourse. We hear simultaneous sounds, but the predominant 

 characteristic of our perception of sounds is that their variety is given 

 in a succession. Hearing is a time-sense. If the ear had remained 

 mobile, it would have been the organ of a space-sense, for it would 

 have given a number of sounds as practically coexisting and as coexist- 

 ing in definite relations to each other; the mobility being lost, hearing 

 has become a time-sense. 



Contrast with the ear's perceptions those of the eye. We look at 

 an object, and so long as we look, its form may remain the same. It 

 may seem to be the same if we look at it after a da) 7 , or a month, or 

 a decade. The great framework of our environment seems to the eye 

 unchangeable. 



It is not to be overlooked that we do perceive changes with the eye. 

 We may watch a cloud melt in the summer sky, or we may call up the 

 image of one who no longer lives. The eye can not ignore the fact 

 of change, as the ear can not entirely ignore coexistence. And it is 

 possible for us to school ourselves to note the changes from hour to 

 hour in what we see. Yet the lesson is not naturally learned by the 

 eye; its world is primarily a spatial world; its interest is in forms and 

 the relations of these forms; for it succession is subordinate, as for 

 the ear coexistence is subordinate. And as far as possible our idea 

 of the stability of forms determines our interpretation of the changes 

 we see. We watch a man walking along the street, or the trees waving 

 in the wind. In such cases we see a change, but our mental reading 

 of it is that a part of the spatial picture has been transferred from 

 one point to another without any alteration in the intrinsic nature 

 of the whole or the parts. It is possible that it is under the influence 

 of the visual imagination that science keeps so persistently to the view 

 that atoms shift their places, but do not suffer change. However this 

 may be, the visual images of objects are spatial and in a measure 

 stable; and they owe this peculiarity largely to the fact that the eye 

 flashes from point to point and considers the external relations of 

 figures to each other, to the comparative neglect of other aspects of 

 reality. 



On the other hand, the immobility of the ear contributes to the per- 

 ception of succession inasmuch as the mind, being unable to get in 

 simultaneity, or what is practically such, all the sounds of the envi- 

 ronment, finds it easier to attend to the series of sounds. If nature 

 had intended to cultivate the power of attending to a successive series 

 of sensations, would not her first steps have been to make the organ 



