XII. 
HEREDITARY INEFFICIENCY. 
Tus world is not, on the whole, a hard world to live 
in if one have the knack of making the proper conces- 
sions. Hosts of animals, plants, and 
men have acquired this knack, and they 
and their descendants are able to hold their own in the 
pressure of the struggle for existence. This pressure 
brings about the persistence of the obedient, those whose 
activities accord with the demands of their environment. 
This persistence of the adaptive is known as the survival 
of the fittest, which has through the ages been the chief 
element of organic progress. Among men there have 
always been those to whom the art of living was im- 
possible. This has been the case under ordinary con- 
ditions as well as under extraordinary ones. It must be 
the case with some under any conceivable environment 
or any circumstances of life. Some variations must 
tend in the direction of incapacity. This incapacity of 
one generation, if inborn and not induced by disease or 
malnutrition, may be handed down by the law of heredity 
to the next. 
In one way or another, in time, most of the incapa- 
bles are eliminated by the process of natural selection. 
But not all of them. Our social system is bound too 
closely. Hereditary incapacity of the few has been in 
all ages a burden on the many who could take care of 
299 
The art of living. 
