5IO THE PHILOSOPHY 



period, as to change the eftablifhed laws of Nature. When the con- 

 ftitution is found, life may, perhaps, by moderating the paffions, and 

 by temperance, be prolonged for a few years. But the varieties of 

 climate, and of the modes of living, make no material differences 

 with regard to the period of our exiftence, which is nearly the fame 

 in the European, the Negro, the Afiatic, the American, the civilized 

 man and the favage, the rich and the poor, the citizen and the pea- 

 fant. Neither does the difference of food, or of accommodation, , 

 make any change on the duration of life. Men who are fed on raw 

 flefh or dried fifh, on fago or rice, on caffada or roots, live as long 

 as thole who ufe bread and prepared vidtuals. If luxury and in- 

 temperance be excepted, nothing can alter thofe laws of mechanifm 

 which invariably determine the number of our years. Any little 

 differences which may be remarked in the term of human life, feem 

 to be chiefly owing to the quality of the air. In general, there are 

 more old men in high than in low countries. The mountains of 

 Scotland, of Wales, and of Switzerland, have furniflied more exam- 

 ples of longevity than the plains of Holland, Flanders, Germany, or 

 Poland. But, if we take a furvey of mankind, whatever be the cli- 

 mate they inhabit, or their mode of living, there is fcarcely any dif- 

 ference in the duration of life. When men are not cut off by acci- 

 dental difeafes, individuals may every where be found who live nine- 

 ty or a hundred years. Our anceftors, with few exceptions, never 

 exceeded this period ; and, fince the days of David King of the 

 Tews, it has undergone no variation. Befide accidental difeafes, 

 which are more frequent, as well as more dangerous, in the latter 

 periods of life, old men are fubjeded to natural infirmities that ori- 

 ginate folely from a decay of the diflPerent parts of the body. The - 

 mufcles lofe their tone, the head fhakes, the hands tremble, the limbs 

 totter, the fenfibility of the nerves is blunted, the cavities of the 

 veflels contrad, the fccretory organs are obftruded, the blood, the 

 lymph, and the other fluids, extravafate, and produce all thofe fymp- 



toms 



