106 WORLD-POWER AND EVOLUTION 



income, and all other drinks are reckoned as part of our food 

 bills. Thus it appears that intelligent people are spending 50 

 per cent more for protection from the air than for both food and 

 drink together. The fact that the most expensive dresses often 

 afford the least protection is neither here nor there. Neither 

 does champagne at five dollars a bottle, or a fancy dessert at a 

 dollar a plate supply as much drink or food as could be obtained 

 for a cent in the form of water or potatoes. 



The fact is that as man advances in civilizaticui^the percentage 

 of effort which he spends upon food and drink steadilx dimiiiishes^ 

 while what he spends on air increases. If the reader is inclined 

 to doubt this, let him ask himself why people spend large sums 

 to go South in winter, or to the seashore and mountains in summer. 

 Is it not for the air? How few people would even consider the 

 plan of going to a summer or winter resort, no matter how fine 

 the scenery, if the air was exactly the same as at home. Why do 

 we do this? Because at last we are realizing that air is not 

 merely something against which we require protection, but some- 

 thing which has a most far-reaching effect upon health and upon 

 all kinds of success in the work of life. And now, in this book, 

 we have seen that air is the great variable in man's environment. 

 Its variations, not only from place to place and season to season, 

 but also from day to day, have far more effect upon his health 

 and work than any other factor or perhaps than all other factors 

 combined. These variations are at the root of all sorts of differ- 

 ences in the capacity of different countries, and also of all sorts 

 of changes in the course of business and hence in politics and 

 other great affairs. 



In view of the extreme importance of the air, it will pay us to 

 turn back to the past and inquire how man happened to become 

 so delicately adapted to one particular kind of climatic environ- 

 ment. How did the air come to control his health to an even 

 greater degree than do food and drink? Why do his attempts to 

 adjust himself to the air become of ever increasing importance 



