152 Heredity and Social Progress 



ment of the motor organs is such that motor 

 reactions arise in every situation, and each 

 failure in adjustment is met by some motor 

 reaction that protects the body. Only sur- 

 pluses can pass this series of defences and 

 become mental phenomena. But centrally 

 excited emotions pass out over the motor 

 organs along routes where no defences have 

 been developed ; they are therefore decadent. 

 Bodily emotions, however, arising, as they do, 

 from an improved discipline, are upbuilding 

 forces. 



The distinction becomes more evident by 

 contrasting the environment of the sensory 

 with that of the motor organs. When defects 

 in adjustment affect a motor organ, it develops 

 instinctive adjustments by which injury is pre- 

 vented. A man going over a rough road 

 calls into action a hundred instinctive move- 

 ments which remedy the defects of the road. 

 The motor environment is provided for by 

 organic adjustments. But no natural safe- 

 guards exist to remedy the defects of the 

 sensory environment. The shocks of non- 

 adjustment go direct to the mind, disturb its 



