HISTORY OF THE ATOMIC THEORY. 29 



the eyes of my fellows, is a coloured medium, probably some 

 modification of blue."* 



Although this paper was an observation on himself, it is in 

 reality a discovery ; the facts had not been arranged before 

 he arranged them, and found out other persons similarly 

 situated. A peculiar keenness of reasoning was needed to 

 find it out, as we must remember that with such persons 

 there is little community of feeling on colour, and scarcely a 

 mode of judging whether they see any colours exactly as the 

 normal eye does. It would probably explain many strange 

 occurrences if we were to consider that there are really per- 

 sons in the world who see all crimsons as " dark blue'* or 

 '* a muddy blue," and who would " match crimsons with 

 claret or mud ; pinks with light blues ; browns with reds ; 

 and drabs with greens ; " who see the healthful tints of a 

 florid complexion to be lik^ " dilute black ink on white 

 paper," or "a dull opake blackish blue, upon a white 

 ground." How many strange mistakes and visions might 

 be accounted for by this defect of sight. A fair face with 

 glowing veins would be lo Dal ton as a corrupting corpse. 

 But it may be said that custom would make all appear as 

 well to him as to others ; no, it cannot be so : a defect must 

 constantly carry with it the consequences of a defect, and in 

 this case the established difference which nature has made 

 between life and death, beauty and horror, was hidden from 

 the eye, and therefore to a great extent must have been 

 concealed from the intellect. To this cause partly we may 

 refer that want of fine sensibility to external things which 

 peculiarly marked his scientific as well as social life. 



Dr. Whewell has called such persons idiopts, because their 

 vision is peculiar ; this is not sufficiently characteristic, and 



• Mr. J. A. Ransome, who examined the eye after death, found nothing 

 whatever to account for the peculiarity of vision. Certainly colours appeared 

 as usual through it. He believed that the cause was a deficient sensorial or 

 receptive power. 



