ORG A NIC E VOL UTION. 7 3 



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in a marvellous degree suited to the performance 

 of their functions and uses, it is nevertheless far 

 from being an invariable rule that the suitability 

 is perfect. Thus, for instance, even in the case 

 of the eye — which is perhaps the most wonder- 

 ful and most highly elaborated structure in 

 organic nature — it is demonstrable that the 

 organ, considered as an optical instrument, is 

 not ideally perfect ; so that, if it were an 

 artificial production, opticians would know how 

 to improve it. And as for instinct, numberless 

 cases might be adduced of imperfection, ranging 

 in all degrees from a slight deficiency to fatal 

 blundering. 



Now if all organic structures are supposed 

 to be mechanisms designed by the Deity, 

 and all instincts are supposed to be mental 

 attributes implanted by Him, it becomes un- 

 intelligible that in the result the human mind 

 should thus be able to perceive, either an 



