252 Mr. Shaw on the * Sense* of Muscular Action 



that originally, as during infancy, all objects are seen inverted, 

 and that some process is required to correct this false impres- 

 sion. But there appears to be no reason for entertaining such 

 a conception. The connexion established between the image 

 upon the retina and the mind which receives the sensation, is 

 altogether so incomprehensible, that no distinction can be sup- 

 posed to depend upon the image being either inverted or erect. 

 There would be an absurdity in speaking of the image being 

 inverted in reference to the mind, which is incorporeal, as we 

 speak of it being inverted in reference to the eye or the external 

 object ; and the process of sensation would not be a whit more 

 intelligible, if the image were placed erect instead of being in- 

 verted. It is more just to believe that the image, of itself, can 

 give no impression whatever of the position of the object, but 

 only those sensations which proceed from light, as the varieties 

 of colour, brightness, shadow, outline, &c. The question is simply, 

 How does the idea of direction first enter the mind ? how do 

 we ascertain that the base of an object is placed towards the 

 ground, and its top towards the skies ? And this question may 

 be considered as one altogether independent of the position of 

 the image at the bottom of the eye. 



If we proceed upon the principle which has been stated 

 above, the answer to this question must be that we judge of 

 the direction of the various parts of a body by ascertaining in 

 what position we must place the eye, in order to see it dis- 

 tinctly. When a tree, for example, is presented to our view, 

 we direct the eyes downwards to observe its trunk rooted in 

 the earth we turn them upwards to see its uppermost branch ; 

 and we turn them to each side to see the right and left sides 

 of the tree : and it is by referring to these motions that we 

 conclude that one part is above, or another is below. In all of 

 these motions, however rapidly performed, a distinct sensation 



- accompanies the change ; and this is communicated to the mind 

 as surely as is the impression upon the retina itself. If we sought 

 for an analogy, we might find it in the hand ; for the law is 



' exactly the same by which we take an object, and touching it 

 -upon one extremity, we say that is its top ; and touching it upon 

 : another, we say that is its bottom. We observe what is the 



* extent of motion of the arm in reaching from its highest extre- 



