146 THE CONTROL OF LIFE 



tinuous role in the neutralisation of acid waste pro- 

 ducts. 



§ 5. What is Disease ? 



It is told of one of the great French chemists, Chev- 

 reul, that when he was interviewed in his hundredth 

 year and asked : " Have you always had a good diges- 

 tion ? " he answered out of the fullness of his vigour : 

 " I really cannot say, for I have never noticed." This 

 is quite ideal ; it indicated a great harmony of inter- 

 nal processes. The antipathy which unsophisticated 

 people have to learning about the works of the living 

 engine, is in a way quite sound. For we really should 

 not know anything directly about organs like the 

 stomach and liver — hard-working structures quite 

 unobtrusive when well used. The body is a great 

 laboratory in which upbuildings and down-breakings, 

 combustions and fermentations, dissolvings and fil- 

 terings go on in crowded order. They are all summed 

 up in the word metabolism, which means change. 

 We may speak of them as vital processes. And the 

 idea we must grasp is that health spells harmony of 

 vital processes, while disease means metabolism out 

 of place, out of time, and out of tune. What is dis- 

 ease in one animal may be normal in another. What 

 would be ominous at one time of life may be natural 

 at another. 



Disease is a disturbance of the body's wholesome 

 routine, and there is progress simply in realising this. 

 Our forefathers thought of disease as a mysterious 



