SUPPLEMENTAL HISTORY OF MAN. 127 



reduction of pressure much more considerable than 

 any above stated. 



This capacity of subsisting and increasing in every 

 latitude, and under every variety of local influence, 

 so curious a phenomenon in the natural history of 

 man, seems partly attributable to his physical con- 

 stitution, and partly to his mental powers. The 

 original source of this very peculiar privilege, is 

 certainly to be found in the properties of the human 

 frame, but the fullest extent to which it is attainable 

 must undoubtedly be referred to the intellectual 

 superiority of man. 



That custom is a second nature in man, is a very 

 trite and a very true observation. Its influence 

 over him is greater than over brutes. But though 

 man is thus the creature, he is very far from being 

 the slave, of custom. There are few, if any, of his 

 habits that he cannot alter or forego with perfect 

 safety, provided he observe a due precaution in the 

 change. His capacity of physical endurance may 

 be increased to a wonderful extent by practice, and 

 that even at a comparatively advanced age. The 

 influence of custom, in this respect, on the body 

 bears a close and striking analogy to that of 

 education on the mind; just as the corporeal 

 capacity, now under consideration, does to that in- 

 definite faculty of intellectual improvement which 

 constitutes the highest privilege, and most glorious 

 distinction of man above every other living being. 



Art, unquestionably, does much to enable man 

 to endure the vicissitudes of climate, and the most 



