FOUNDATIONS OF RATIONAL TREATMENT. 393 



our clothing, our sources of heat ; we may admit into our 

 bodies substances which we find in nature mineral, vegetable, 

 animal, or altogether artificial. On the other hand, we may 

 voluntarily shun or reject such substances, and avoid many 

 influences, whether for good or for bad, around us. To express 

 this control which we have over our organs and functions, 

 through the conditions to which we can voluntarily 

 subject them, we say we act physiologically upon them by such 

 and such means, or that such and such a substance has such and 

 such a physiological action ; and the science that relates to this 

 power which we possess of modifying physiological activity we 

 call Pharmacodynamics. 



3. Pathology. The conception of disease is also included 

 in " treatment." When the conditions which surround us become 

 unusual or extraordinary, they lead to disturbance of the vital 

 processes. If this be moderate, it is still included under the name 

 of "health;" but if considerable, it is called disorder or disease, 

 and the influence is called a morbid influence. It is essentially 

 impossible to draw a line between health and disease, just as it 

 is impossible to divide influences into salutary or physiological, 

 and morbid or pathological. The pulse is accelerated by joy, 

 by wine, by fever ; which of these conditions is health, which 

 disease ? All that can be said is, that the change from the 

 normal state is frequently so definite that we cannot 

 reasonably call it "health," that we must find another name 

 for it, and call it " disorder ; " or if it be more marked, and 

 attended by. suffering, " disease." 



4. Recovery. Successful treatment necessarily involves a 

 power of recovery. The body possesses abundant provisions for 

 preventing disease, and of recovering from its effects. This 

 power of meeting and overcoming morbid influences depends 

 essentially on the great physiological law which we have 

 already noticed, that the activity of the tissues and organs 

 is not fixed and constant, but varies (within certain limits) 

 with the conditions to which it is subjected. The body is 

 abundantly provided with the following means by which this 

 variation of functional activity can be secured : 



First, when occasion demands it, the organs can display an 

 extraordinary amount of force, as we see in the case of a muscle 

 such as the biceps, or the heart. The organs thus possess a 

 certain amount of reserve force, which is frequently called into 

 play as a means of preventing disease. But for this, we should 

 break down in every part of our body as often as we made an 

 extra demand upon it. 



Secondly, if this reserve force be constantly called into 

 play by the continuance of some extraordinary cause, the 



