SIGHT. 583 



according to Gall, the organ for judging of the harmony of colours 

 is placed, is flat or depressed. I have seen several of these cases, 

 and in all this was the fact. In painters, remarkable for their ex- 

 cellence of colouring, this part is full or prominent. The con- 

 trast between this part of the forehead in a person who has the 

 defect, and in another excelling in the power of colouring, placed 

 side by side, is very striking. 



Professor Dugald Stewart remarks that, " in the power of con- 

 ceiving colours there are striking differences among individuals;" 

 and he does not ascribe the difference to the eyes. " I am inclined 

 to suspect," he says, " that in the greater number of instances the 

 supposed defects of sight ought to be rather ascribed to a defect 

 in the power of conception." b Mr. Stewart is correct in exempt- 

 ing the eye from blame, and ascribing the defect to a defect in 

 conception ; but, since he has no idea of a distinct faculty for 

 colours, he means conception in general. Yet, as the individuals 

 are not deficient in other conceptions, some reason must be given 

 for the deficiency of conception in this one point. He thinks it 

 arises " probably in consequence of some early habit of inatten- 

 tion." Now this is sad trifling in a philosopher. What particular 

 attention do children, who distinguish colours accurately, bestow ? 

 They distinguish without effort ; and those who cannot, are not 

 only not proved to have been inattentive, but have, most probably, 

 been often extraordinarily attentive, in the hope of seeing what 

 others can see. How should want of attention to this one point 

 run in families and be hereditary, passing through a generation, 

 &c. ? This is a specimen of the errors of metaphysicians. They 

 see, and generally acknowledge, that the brain is the organ of the 

 mind ; yet they observe the faculties of the mind without even 

 once considering the organ which possesses, or is employed in the 

 working of, these faculties. Gall examined the two together, and 

 we now know through him that local deficiency of brain both 

 exists where the power of distinguishing colours is deficient, and 

 is hereditary with this deficiency. 



Motion of the eyes. The eye is moved by six voluntary 

 muscles, four straight, a superior, inferior, external, and in- 

 ternal ; and two oblique, a superior, with its tendon running round 

 a pulley, and an inferior. 



b Elements of the Philosophy of the Human Mind, ch. Hi. 



