WHY IS THE HUM AX EAR IMMOBILE? 229 



cauce of this loss can be better understood if we consider for a little 

 such a sense as sight. 



The eye is movable and is continually shifting its position. From 

 this mobility two results follow which in the present connection it is 

 important to notice. First, the eye can be readily turned so as to get 

 the clearest vision of any object that is to be examined. We do not 

 see equally well with all parts of the eye; we see most distinctly with 

 the central part directly opposite the pupil, and when there is anything 

 seen out of the corner of the eye which we wish to observe more closely, 

 the eye is, in normal circumstances, turned upon it so as to catch the 

 image in this central part. Spontaneously and accurately these 

 changes in the eye's direction are made. It can readily be understood 

 that great help to our perception is gained from them. 



There is another result of this free movement which is of equal 

 importance. To it is due the orderly spatial arrangement presented 

 by the world of our vision. It may seem that our knowledge of the 

 position of things in relation to each other is natural or instinctive, 

 and we may be pointed to the behavior of many animals which are 

 able to guide their movements correctly as soon as they enter the 

 world. But such reflex activities do not seem to be strictly parallel 

 to those of the human child. That the child has in its nervous sys- 

 tem inherited a predisposition to its future adjustments, may be true. 

 But it is also true that it does not respond to its surroundings as the 

 chick, for instance, does ; it gains its conscious appreciation of external 

 relations by experience. What the child's first experience of sight is, 

 it is difficult for the adult to guess; yet some of our perceptions ap- 

 proach to it. The German psychologist Volkmann von Volkmar calls 

 attention to the fact that when we gaze into the blue depths of the 

 sky our color perception has a character similar to that of a musical 

 note. Probably our visual sensations are all, in their original intrinsic 

 nature, of this sort; color feelings with no idea of position as yet 

 developed. It is further to be noted that we might have a succession 

 of color pictures, such as can be afforded by familiar mechanical 

 devices, without any suggestion as to the spatial relations of these 

 various pictures. And were the eye incapable of movement of any 

 kind, its experiences would be a mere succession of vaguely voluminous 

 color-feelings. But, on the other hand, let the eye be considered as 

 capable of movement, and as free to play among these colors ; it passes, 

 say, from the image of the door to that of the wall, and then to that 

 of the window. It is not less important to notice that it can by its 

 power of movement reverse the series and pass from window to door. 

 Such series may, to an indefinite extent, be increased, repeated, re- 

 versed. Thus the mind gets the idea of a series of images relatively 

 permanent, always open to observation, and arranged in a perfectly 



