98 THE CAUSATION OF DISEASE. 



It is impossible for the physician to exaggerate the import- 

 ance of the vis medicatrix naturce. It shows him how much 

 he has to hope from a careful regulation of the E, not only 

 in acquired disease, but in inherited tendencies ; it makes him 

 feel, under a crushing sense of the terrible power of heredity, 

 that he has yet within his hands the means by which he can 

 do successful battle with it. His problem, in any case of 

 hereditary tendency, becomes how to produce a reversion by 

 placing the individual, as far as possible, in an E as like that 

 of his primitive ancestors as the altered conditions of life 

 will allow, and to supplement or correct this E by care- 

 fully applying the medical knowledge he has so laboriously 

 acquired. 



We may here fittingly turn aside for a moment to inquire 

 into the nature of such an E. From the habits of the primi- 

 tive savage we learn that man was intended to live in the open ; 

 — or, to speak more scientifically, he has evolved from a lowly 

 being under an exposed E ; to go no further back than his simian 

 ancestors, we find them living in the open, under no other shelter 

 than that afforded by the branches of trees. Man having then 

 evolved under exposure — beneath the free canopy of heaven, 

 it follows that he must be, in the main, adapted to a life of 

 exposure, — not, like the mole, to a subterranean existence, 

 nor, like the whale, to an aquatic life. Now, both of these 

 last-named animals have evolved from ancestors living upon 

 the dry land, by gradual adaptation to a changing E. In like 

 manner and through unnumbered generations the human body 

 has been changing in response to a changing E ; and it might 

 be argued that, just as the mole has become modified for 

 a life underground, and the whale for an aquatic life, so has 

 primitive man become structurally adapted to a life spent 

 under a roof. But he has not. As we shall see later on, 



recovery from the morbid conditions transmitted from parents: a tendency 

 to revert to the true healthy type of structure and composition. Such a 

 tendency would be in accordance with the general rule of tendency to rever- 

 sion from all variations of specific characters, and would be a part of that 

 tendency to recovery of health which suggested a vis medicatrix naturce, and 

 which we may observe through life, diminishing as age increases, but never 

 quite lost." — Clinical Lectures, by Sir J. Paget, p. 408. 



