2 32 THE POPULAR SCIENCE MONTHLY 



cific serum and vaccine treatment of certain diseases, of prophylactic 

 measures, and of the specific methods of diagnosis. 



The tremendous and revolutionary advance made by medicine in the 

 past few decades is obvious to the most superficial view. It is quite ap- 

 parent that internal medicine has just been having its Kenaissance, even 

 within the lifetime of men now living having passed through that stage 

 of development that other departments of human thought and activity 

 passed through centuries ago. We have only just emerged from the 

 middle ages in medicine. The movement is still in unabated activity. 

 The final goal is far from having yet been reached, and there are vast 

 fields in medicine yet to be cultivated before the one-sided and partial 

 developments of the past will be amplified into a more symmetrical and 

 perfect form. With medical research and progress continuing at the 

 present rate, the outlook is rich with promise for the future develop- 

 ment of medicine and added benefits for mankind. 



In looking over its history we can distinguish the operation of two 

 contrary tendencies or methods of thought which have controlled the 

 evolution of medicine. These two principles mark off the history of 

 medicine into two epochs, the speculative and the scientific, of a dis- 

 tinctiveness more fundamental than the ordinary division into such 

 periods as the ancient, Arabian and medieval. These two factors are: 

 (1) the subjective, deductive, a priori or speculative, and (2) the 

 objective, inductive, a posteriori, empirical or scientific, methods of 

 attaining knowledge. 



The subjective or speculative method is the one that prevailed 

 throughout medical history down to the modern era. It is far the 

 more attractive and has much the stronger hold on human nature; it 

 is the primitive and natural method of the untrained mind. It is easy 

 and pleasant to construct complete schemes of the universe by intro- 

 spection. Scientific investigation is tedious and laborious, and leaves 

 many gaps in knowledge. There is a demand in human nature for 

 certainty, and completeness, and finality in knowledge. Our patients, 

 for example, demand this in our diagnoses and prognoses. The mind 

 is impatient with the unknown, and is prone to fill up the blanks in 

 knowledge by premature generalizations and assumptions. 



The objective or empirical method of gaining knowledge is the one 

 that characterizes modern science. Eigidly suppressing preconceived 

 notions and bias, this method proceeds by painstaking observation and 

 investigation to collect an adequate mass of objective data as a pre- 

 requisite to generalization. This method is not natural to human 

 nature, but is a product of culture. In the history of mankind, it was 

 ages before, in the Eenaissance, it came to dominate the best thought; 

 and among the mass of people at the present time it is only a cultured 

 few who are thoroughly imbued with its spirit. 



