34 THE METHODS AND 



usefulness in our work. Genetic inquiry aims 

 at providing knowledge that may bring, and 

 I think will bring, certainty into a region 

 of human affairs and concepts which might 

 have been supposed reserved for ages to be 

 the domain of the visionary. We have long 

 known that it was believed by some that our 

 powers and conduct were dependent on our 

 physical composition, and that other schools 

 have maintained that nurture not nature, to 

 use Galton's antithesis, had a preponderating 

 influence on our careers; but so soon as it 

 becomes common knowledge not a philo- 

 sophical speculation, but a certainty that 

 liability to a disease, or the power of resisting 

 its attack, addiction to a particular vice, or to 

 superstition, is due to the presence or absence 

 of a specific ingredient ; and finally that these 

 characteristics are transmitted to the off- 

 spring according to definite, predicable rules, 



