LESSONS OF EVOLUTION 627 



conditions, internal as well as external, of its life and growth. 

 The primitive intelligence is useful to the organism as a 

 more elastic method of adjusting itself to its environment. 

 As the mental powers develop, the tables are turned, and 

 the mind adjusts its environment to its own needs. ' Mihi 

 res non me rebus subjungere conor ' is the motto that it 

 takes for its own. With the mastery of external nature, ap- 

 plied science has made us all familiar. But the last enemy 

 that man shall overcome is himself. The internal conditions 

 of life, the physiological basis of mental activity, the socio- 

 logical laws that operate for the most part unconsciously, 

 are parts of the ' environment ' which the self-conscious in- 

 telligence has to master, and it is on this mastery that the 

 regnum hominis will rest' (Hobhouse, 1915, p. 443). Of 

 a truth, Science is for Life, not Life for Science. 



SUMMARY. 



The theoretical doctrine of evolution has for its practical corollary 

 the fact of the controllability of life. Darwin was logically fol- 

 lowed by Pasteur. 



If the central fact in evolution be " the slowly wrought-out dom- 

 inance of mind in things ", it is surely man's fundamental task to use 

 this expanding mind for the fuller possession of his kingdom, and 

 the better ordering of his life in it. If evolution suggests any les- 

 son it is this. We must inquire, therefore, into the determinants of 

 life. 



The first determinant of life is heredity our relation to preceding 

 generations which includes not only the past living on in the 

 present, but new departures or variations. We cannot alter our own 

 inheritance, though it is ours to trade with, but we have some meas- 

 ure of control over the inheritance of future generations. 



The second determinant of life is nurture all manner of for- 

 mative influences from surroundings and from use and disuse 

 and this is largely controllable in our hands. Nurture determines 

 the fulness of expression that hereditary characters may attain in 



