PHYSIOLOGY AND HEALTH 



CHAPTER I 



THE LIVING MATERIAL OF THE BODY 



"Know thyself" was a motto of the ancient Greeks. Wise 

 as such advice was in their day, it is far more necessary in 

 these modern times of complex civilization. The Greeks 

 knew less than we of the activities of the body organs, but 

 they needed such knowledge less because their mode of living 

 was simpler. Their lives were passed largely out of doors, 

 never in close houses; their food was plain, but nourishing 

 and abundant; their bodies were vigorous and active 

 because they exercised all their muscles. 



But to-day people are so crowded into cities that there 

 is little time or opportunity for physical exercise and there is 

 every facility for the distribution of contagious diseases. 

 We shut ourselves up in close houses, thus depriving ourselves 

 of needed air; we use trolleys, carriages, automobiles, tel- 

 ephones and mails to save the time and trouble of walking, 

 we eat an endless variety of good and bad foods, variously 

 prepared and often adulterated; we live in the midst of 

 more or less constant and intense activity. Brain work 

 takes the place of muscle work with part of the race while 

 another part uses the brain very little. 



Amid all these complexities the problem of retaining health 

 and vigor is increasingly difficult. In our crowded cities 

 people are living under unnatural conditions, and serious 



