186 EFFECTS OF WEATHER CHAP. 5. 



operating to produce ill health, that the extent 

 of the influence of any one can hardly be ascer- 

 tained. Inactive habits of life, bad air, irritating 

 food, the drinking of spirituous and fermented 

 liquors, the misguidance of the appetites, and 

 the reciprocal operation of the mind and body 

 on each other, have all a tendency to produce 

 disease. But though these various evil habits 

 of artificial life all act to our detriment, their 

 kind of influence may be somewhat different : 

 and in proportion as families, and even nations,* 



* In the production of national varieties, local situation is 

 probably much concerned ; and, in this case, the influence of 

 the atmosphere, in their production, does not seem to depend 

 on the degree of heat alone : for not only the colour of the 

 skin and hair, but the form and countenance, and also the 

 diseases of different nations inhabiting nearly the same 

 latitude, vary considerably. The varieties of the soil and its 

 vegetable productions, which constitute part of their food, 

 may have a degree of influence; and so may peculiarities 

 in the electric state of the air in different longitudes : but 

 there are hordes of savages inhabiting the same tract of 

 country, and living in near neighbourhood, which differ much 

 from each other. And we may add, that among people of the 

 same nation there are scarcely two heads and consequently no 

 two minds exactly alike. It is remarkable, that this variety 

 of figure, of expression of countenance, and apparantly of 

 kind of mind, is increased in proportion as man becomes 

 civilized. The number and variety of its diseases are also 



