THE BIOLOGICAL SCIENCES AND MEDICINE. 



vision, is a process, and the chain of causation involved 

 in that process. Disease, as we have seen, is a perturba- 

 tion of the normal activities of a living body, and it is, 

 and must remain, unintelligible, so long as we are ig- 

 norant of the nature of these normal activities. In other 

 words, there could be no real science of pathology until 

 the science of physiology had reached a degree of per- 

 fection unattained, and indeed unattainable, until quite 

 recent times. 



So far as medicine is concerned, I am not sure that 

 physiology, such as it was down to the time of Harvey, 

 might as well not have existed. Nay, it is perhaps no 

 exaggeration to say that, within the memory of living 

 men, justly renowned practitioners of medicine and sur- 

 gery knew less physiology than is now to be learned 

 from the most elementary text book ; and, beyond a few 

 broad facts, regarded what they did know as of ex- 

 tremely little practical importance. Nor am I disposed 

 to blame them for this conclusion ; physiology must be 

 useless, or worse than useless, to pathology, so long as 

 its fundamental conceptions are erroneous. 



Harvey is often said to be the founder of modern 

 physiology ; and there can be no question that the elu- 

 cidations of the function of the heart, of the nature of 

 the pulse, and of the course of the blood, put forth in 

 the ever-memorable little essay, "De motu cordis," di- 

 rectly worked a revolution in men's views of the nature 

 and "of the concatenation of some of the most important 

 physiological processes among the higher animals ; while, 



