CHAPTER VII 

 THE VOYAGE OF EVOLUTION 



FOOD, drink, air. These, as we have seenf are the three 

 primary needs of life. Probably three fourths of all man's 

 efforts are directed toward obtaining food. That is why 

 food figures so largely in all discussions of health and economics. 

 Effort is also required in order that the right kind of drink may 

 be available in proper quantities. Therefore we spend vast sums 

 for waterworks, and count the liquor question as one of our 

 greatest problems. But air, we have been wont to say, is different. 

 If food were "free as air," most of mankind would sit around and 

 do nothing a large part of the time. Hitherto the vast majority 

 of mankind have thought of air chiefly as something against 

 which we require protection. For this protection we have gone 

 to vast labor in order that we may have clothes and shelter. As 

 civilization has advanced these items have become of growing 

 importance. Although the world as a whole may devote three 

 fourths of its energy to obtaining food, Mrs. Richards, in her 

 little book, "The Cost of Living," estimates that among sensible 

 people in comfortable but not affluent circumstances about 20 

 per cent of the income is spent for rent, 3 to 5 per cent for fuel, 

 and 15 per cent for clothing. Food, on the other hand, should 

 require 25 per cent of the total income. Thus today among (y^ 

 people of the kind who will read this book the amount spent for 

 protection against the air averages about one and one-half times 

 as much as is spent for food. But remember that in ordinary 

 discussions of domestic economy, drink is counted with food. 

 Our bills for water do not amount to 1 per cent of an ordinary 



