44 THE POPULAR SCIENCE MONTHLY. 



thankful to say, taught, if not practiced, in almost every schoolroom 

 and factory in England, are the direct results of the abstruse researches 

 of Boyle and Priestley, of Lavoisier and Pasteur. Ages of experience 

 did not teach mankind the value of fresh air, or the innocence of clean 

 water. Indeed, I have myself heard astonishment expressed by a Ger- 

 man professor at the peculiar immunity with which English skins will 

 bear the daily and unstinted application of soap and water. 



If the art of keeping a community in health is but the application 

 of plain physiological laws, it is no less true that the art of restoring 

 the health, curative as distinct from preventive medicine, rests upon 

 the same basis. In former days the physician was one who recognized 

 what he called the disease of his patient, who referred to his books of 

 precedents as a lawyer to his statutes, and who prescribed a proper 

 remedy to cast out the disease. We now know that disease is, as the 

 name implies, a purely subjective conception. The disease of a host 

 is the health of the parasite, and we cure a human sufferer by poison- 

 ing the animals or plants which interfere with his comfort. The same 

 changes which in the old man are the natural steps of decay, the ab- 

 sence of which after a certain age would be truly pathological, are the 

 cause of acute disease in the young. Pathology has no laws distinct 

 from those of physiology. 



When these now obvious considerations are thoroughly understood, 

 it clearly follows that all "systems of medicine" are in their very 

 nature condemned. All that the art of medicine can do is to apply a 

 knowledge of natural laws, of mechanics and of hydrostatics, of bota- 

 ny and zoology, of chemistry and electricity, of the behavior of living 

 cells and organs when subjected to the influence of heat and of cold, 

 of acids and alkalies, of alcohols and ethers, of narcotics and stimu- 

 lants, so as to modify certain deviations from ordinary structure and 

 function which are productive of pain, or discomfort, or death. It is, 

 therefore, plain that rational medicine, or keeping right and setting 

 right the human body, must rest upon a knowledge of its structure and 

 its actions, just as a steam-engine or a watch can not be mended upon 

 general principles, but only by one who is familiar with their construc- 

 tion and working, and who can detect the source of their irregularity. 



An objector may say : " Admitting that medicine is an art, it is a 

 purely empirical art. You can not detect the origin of many of the 

 maladies which you are yet able to cure ; your best remedies have not 

 been obtained by scientific experiment, but by chance, observation, and 

 accumulated experience ; and, if you doctors would give more time to 

 practical therapeutics, that is, to finding out what is good for the sev- 

 eral aches and pains we complain of, you would spend your time better 

 than in abstruse researches into microscopic anatomy or the properties 

 of a dead frog's muscle." 



The answer to the objection is an appeal to fact. For centuries so- 

 called observation and experience left medicine in the condition it 



