24 MEDICINE 



causative agencies acting on the tissue, produce structural alter- 

 ations, in consequence of which even the action exerted by the or- 

 dinary surroundings may result in disharmony. The terms health 

 and disease both carry with them the conception of activity. Al- 

 though the abnormality of function is always associated with and 

 depends upon structural alteration, there may be extensive struc- 

 tural alteration which is so repaired or compensated for that it 

 does not result in disease. 



In the history of the advance of knowledge in medicine we rind 

 two methods by which knowledge has been sought. In one, the 

 endeavor has been made to form conceptions of the objects studied 

 by means of impressions conveyed by the senses. Great advances 

 have always followed the discovery of methods and instruments 

 by means of which the territory of investigation has been extended. 

 The inquiry does not stop with the mere description of the concep- 

 tions derived from the sense-impressions, but an effort is made to 

 correlate them, to ascertain preceding conditions, and the meaning 

 or idea involved. When the inquiry passes beyond the immediate 

 investigation, an ideal conception of the nature, the interrelation, 

 the cause or the result of the conditions studied, an hypothesis, 

 may be formed, based on experience and analogy. The hypothesis 

 must be tested by further observation under natural conditions and 

 by the experiment which involves observation under known and 

 controlled conditions. When the hypothesis has been so tested 

 and found to hold good in all cases under the same conditions, it 

 can be used as a basis from which new questions may arise. 



The other method is by speculation. By a wide and illegitimate 

 use of analogy conceptions are formed and projected into the objects, 

 instead of being derived from the sense-impressions. A tendency 

 to speculation is inherent in the nature of man. Confronted al- 

 ways with the unknown, which has such enormous proportions 

 compared with the known, and so much of which seems to be re- 

 moved from the possibility of actual investigation, man is led to 

 attempt to answer the questions which the unknown thrust upon 

 him by means of the imagination. As knowledge becomes deeper 

 and more extended, speculation tends to become more confined. 

 True philosophy aims at a complete understanding of the causal 

 relation of all processes in nature and of man's relation to these 

 processes. Disease, as one of the most important conditions in 

 nature affecting man in all of his relations, has always had an im- 

 portant place in philosophy. All the systems of philosophy in the 

 past, from Plato down, have embraced speculations concerning 

 disease. The true ends of philosophy cannot be reached by specu- 

 lation, but by the use of all the material for observation given by 

 the natural sciences, and a philosophic system will contain just so 



