Heredity and the Law of Evolution. 305 



These remarks also apply in every respect to nations and 

 races : all that is required is that the destructive influences should 

 bear, not on an isolated individual, but upon a mass of individuals. 

 The mechanism of decay is identical in the two cases ; and we are 

 justified in the conclusion that the causes which, in the narrow 

 world of the individual and the family, produce a considerable 

 diminution of the intellectual forces, must produce the like effect 

 in that agglomeration of individuals which constitutes a society. 



Historians usually explain the decline of nations by their manners, 

 institutions, and character, and in a certain sense the explanation 

 is correct. These reasons, however, are rather vague, and, as we see, 

 there exists a more profound, an ultimate cause an organic cause, 

 which can act only through heredity, but which is altogether over- 

 looked. These organic causes will probably be ignored for some 

 time to come, but our ignoring them will not do away with them. 

 As for ourselves, who have, for purposes of our own, attempted to 

 study the decay of the Lower Empire the most amazing instance 

 of decay presented by history tracing step by step this degeneration 

 through a thousand years : seeing, in their works of art, the plastic 

 talent of the Greeks fade away by degrees, and result in the stiff 

 drawing, and in the feeble, motionless figures of the Paleologi ; 

 seeing the imagination of the Greeks wither up and become 

 reduced to a few platitudes of description ; seeing their lively wit 

 change to empty babbling and senile dotage ; seeing all the 

 characters of mind so disappear that the great men of their latter 

 period would elsewhere pass only for mediocrities it appears to 

 us that beneath these visible, palpable facts the only facts on which 

 historians dwell we discern the slow, blind, unconscious working 

 of nature in the millions of human beings who were decayed, 

 though they knew it not, and who transmitted to their descendants 

 a germ of death, each generation adding to it somewhat of its own. 



Thus, in every people, whether it be rising or falling, there exists 

 always, as the groundwork of every change, a secret working of 

 the mind, and consequently of a part of the organism, and this 

 of necessity comes under the law of heredity. 



Here we bring to a close our general study on the consequences 

 of heredity. We must next look at the details. In order to pro- 

 ceed with the inquiry methodically, we will proceed from causes 



