THE PROBLEMS OF THERAPEUTICS 171 



derstands the reason why their procedure is useful. It is only when 

 we learn the reason why that an art becomes converted into a sci- 

 ence. Therapeutics in its primitive form is one of the simplest of 

 all the arts and is practiced by animals as well as by man, but as 

 a science it is one of the most complex and most difficult of all be- 

 cause it requires a knowledge of the functions of the body in health, 

 or physiology; of their changes in disease, or pathology; of the 

 action of drugs upon the body, or pharmacology; and of chemistry, 

 physics, and other sciences on which physiology, pathology, and 

 pharmacology are based. Finally it requires the practical power 

 of recognizing from the symptoms (in any individual case) the 

 nature of the pathological changes present and the ability to apply 

 the right methods of treatment in order to counteract these changes 

 and heal the patient. It is evident that such complex knowledge 

 as this must be very difficult of attainment, yet nevertheless the 

 change of therapeutics from an art into a science is progressing 

 with considerable rapidity. In a text-book on the subject which 

 I published eleven years ago, I mentioned the use of quinine in ague 

 as the best example of the art of therapeutics whereby we could 

 cure a disease of which we did not know the nature by a remedy 

 whose curative action we did not understand. Since that time, 

 however, we have learned that ague depends upon the presence 

 of a foreign organism in the body and that the benefits obtained 

 from quinine are due to its poisonous action upon this intruder. 

 This malarial parasite is only one of the many minute organisms 

 which mar or destroy the health of the human body. Minute organ- 

 isms or microbes are most useful in their proper place and without 

 them the world would be uninhabitable because they are the nat- 

 ural scavengers which produce putrefaction in dead plants and 

 animals and thus bring about their return to dust, fitting them 

 for new life instead of allowing them to incumber the ground. But 

 not content with this function, some of them proceed to invade 

 living beings, attacking not only the weak but even the strong, and 

 by growing and multiplying within them weaken or destroy their 

 hosts. 



One of the great problems of therapeutics, then, is to defend the 

 body from attacks of microbes. This may be done either (a) by 

 weakening or destroying the microbes themselves or (&) by in- 

 creasing the power of the organism to resist them. 



It is convenient to speak of the body as a whole when we are dis- 

 cussing its invasion by microbes, but we must not forget that the 

 body, like a country, is composed of many parts. The interests of 

 the different parts are by no means identical, and while they generally 

 act together for the common good they may not always do so, and 

 either by their sluggishness and inaction or by their mischievous 



