Pai] AND SYMBOLS. 257 



animal has reached, after numberless generations, the deepest 

 recesses, disuse will on this view have more or less perfectly 

 obliterated its eyes. no. 



Nature's Provision against Overcrowding. 



The natural safeguard against overcrowding is emigration. 

 We see this beautifully illustrated in the case of the star-fish. 

 The larva of the star-fish is an active, free-swimming animal, 

 having a long body with six slender arms on each side, from one 

 end of which the young star-fish is (so to speak) budded off; 

 and when this has attained a certain stage of development, the 

 long twelve-armed body separates from it and dies away, its 

 chief function having apparently been to carry the young star- 

 fish to a distance from its fellows, and thus to prevent over- 

 crowding by the accumulation of individuals in particular spots, 

 which would be liable to occur if they never had any more active 

 powers of locomotion than they possess in their adult state. 



MI. 



The Relation of Pain to Pleasure. 



Sensation is modified both by the condition of the body and 

 by the state of the mind with regard to it. Thus we find that 

 in the peculiar condition of mind and body attending mesmeric 

 sleep (according to the testimony of honest witnesses, who 

 are to be believed), persons may have their limbs removed 

 without pain, and the exposed extremities of the divided 

 nerves being roughly handled, causes only a sensation of 

 titillation, under which the patient laughs like a tickled 

 child. Pain, indeed, is but the excess of an impression 

 which, in a milder form, is pleasure; and the same degree 

 of impression is either one or the other, according to the state 

 of attention at the time, or according to the association of the 

 mind. In many respects pain is really an acquired feeling, 

 like fear, and it arises from the mind being taught to associate 

 certain sensations with the idea of danger. Thus when the 

 Esquimaux first had razors given to them, they used to gash 

 their tongues for the pleasure of the new sensation of being cut 

 with so keen an instrument ; but after they learned there was 



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