182 PSYCHOLOGY. 



world by farther experiences which shall alter its bulk, 

 identify its directions, fuse its margins, and finally imbed it 

 as a definite part within a definite whole. And even though 

 every joint's rotations should be felt to vary inter se as so 

 many differences of direction in a common room ; even 

 though the same were true of diverse tracings on the skin, 

 and of diverse tracings on the retina respectively, it would 

 still not follow that feelings of direction, on these different 

 surfaces, are intuitively comparable among each other, or 

 with the other directions yielded by the feelings of the 

 semi-circular canals. It would not follow that we should 

 immediately judge the relations of them all to each other 

 in one space-world. 



If with the arms in an unnatural attitude we ' feel ' 

 things, we are perplexed about their shape, size, and 

 position. Let the reader lie on his back with his arms 

 stretched above his head, and it will astonish him to find 

 how ill able he is to recognize the geometrical relations of 

 objects placed within reach of his hands. But the geomet- 

 rical relations here spoken of are nothing but identities 

 recognized between the directions and sizes perceived in 

 this way and those perceived in the more usual ways. 

 The two ways do not fit each other intuitively. 



How lax the connection between the system of visual and 

 the system of tactile directions is in man, appears from the 

 facility with which microscopists learn to reverse the move- 

 ments of their hand in manipulating things on the stage of 

 the instrument. To move the slide to the seen left they 

 must draw it to the felt right. But in a very few days the 

 habit becomes a second nature. So in tying our cravat, 

 shaving before a mirror, etc., the right and left sides are 

 inverted, and the directions of our hand movements are the 

 opposite of what they seem. Yet this never annoys us. 

 Only when by accident we try to tie the cravat of another 

 person do we learn that there are two ways of combining 

 sight and touch perceptions. Let any one try for the first 

 time to write or draw while looking at the image of his 

 hand and paper in a mirror, and he will be utterly bewil- 

 dered. But a very short training will teach him to undo 

 in this respect the associations of his previous lifetime. 



