542 Darwinism and History 
of genetic history or at least followed in the footsteps of those who 
fully grasped the genetic point of view. But their aim has been to 
collect and sift evidence, and determine particular facts; com- 
paratively few have given serious thought to the lines of research and 
the speculations which have been considered in this paper. They 
have been reasonably shy of compromising their work by applying 
theories which are still much debated and immature. But historio- 
graphy cannot permanently evade the questions raised by these 
theories. One may venture to say that no historical change or trans- 
formation will be fully understood until it is explained how social 
environment acted on the individual components of the society (both 
immediately and by heredity), and how the individuals reacted upon 
their environment. The problem is psychical, but it is analogous to 
the main problem of the biologist. 
