Unity of Life 123 



fiable working hypothesis but a simple comprehensible fact. 

 Physiological science reveals the individual in exactly the 

 complex form which a study of conduct appears to indi- 

 cate. The science of the evolution of species and varieties 

 of animal life, leads from questions of detail, back to pri- 

 mary laws, and to fundamental nature. This science reveals 

 in convincing evidence, visible at any time, the way in which 

 nature works to produce the physical forms of life, and it 

 is found to be the same way in which the details of conduct 

 are compensated and minute advantages of fitness rewarded. 

 The continuation or extinction of the life term is the way 

 in which for all past ages evolution has advanced material 

 life to higher physical forms, while the compensation for 

 conduct has proceeded. Acts and consequences accumu- 

 lating in error or in right, which may exterminate life or 

 extend it now, operate under a law which always was. 

 Ever since life began there has been the same continued 

 rewarding of the fittest by the lease of life. But this reward 

 was not bestowed upon creatures who merely suffered it. 

 These promoted to the higher grades were not passively but 

 actively fit. As we see now, they became and continue fit 

 by changes of activity which suited their environment of 

 conditions and circumstances, as well as by persistence in 

 things they inherited which continued to be beneficial. The 

 changes are proven to have occurred, both in the circum- 

 stances and the creatures, not only by inference from their 

 present condition of progress ; but by the positive geological 

 records of fossilized life covering countless ages. Knowl- 

 edge of this continual change comes down from all times, 

 and in all ways, to show it to be perpetual. 



