THE CAUSATION OF DISEASE. 319 



developed thereby. We first find it existing among the dif- 

 ferent members of a family — notably, between mother and 

 child, in the form of instinctive affection ; then among the 

 different members of a tribe, taking the form of crude laws ; 

 and, finally, among the different members of a nation. But what 

 is noticeable is that, at first, there is no sense of any obliga- 

 tion extending beyond these comparatively narrow limits ; there 

 is no recognition of the moral tie between family and family, 

 tribe and tribe, nation and nation. A certain code of morality 

 among the individuals of each of these aggregations is abso- 

 lutely necessary to its separate existence, but it is not 

 equally necessary that any morality should exist between 

 the separate aggregations themselves. Hence we often find 

 it altogether absent, and perpetual warfare going on between 

 them. But just as families have united to form tribes, 

 and tribes to form nations, and these again to form larger 

 nations, so, in course of time, we may look for the latter 

 uniting to form one vast federation ; and then, but not 

 till then, the obligations always existing between the com- 

 munities into which mankind naturally falls, will be recog- 

 nized, and warfare cease. Thus, the conduct of individuals 

 towards one another must become more and more exact as 

 civilization advances, and since the moral principles thus in- 

 culcated from generation to generation leave upon the mental 

 organization an actual impress which tends to be inherited, 

 it follows that with progressive civilization the moral faculty 

 grows stronger and stronger. 



Such an evolution of morality rests upon the principle 

 of heredity. It assumes the capacity of heredity to trans- 

 mit fine shades of mental alteration, and this capacity has 

 been, as I observed just now, long recognized by biographers 

 and writers of fiction. Mr. Henry Drummond points out 

 how careful the former are to study in detail the working 

 of hereditary influence. " Students of biography," says he, 

 ' 4 will observe that in all well-written lives attention is concen- 

 trated for the first few chapters upon two points. We are first 

 introduced to the family to which the subject of the memoir 

 belonged. The grand-parents, or even the most remote ances- 

 tors, are briefly sketched, and their chief characteristics brought 



