6 SCIENCE PROGRESS. 



be permitted to repeat what has been already said, we use 

 the evidences of adaptation differently. We found no ex- 

 planation on this or any other biological principle, but refer 

 all the phenomena by which these manifest themselves to 

 the simpler and more certain Physical Laws of the Universe. 



Why must we take this position ? First, because it is a 

 general rule in investigations of all kinds to explain the 

 more complex by the more simple. The material Universe 

 is manifestly divided into two parts, the living and the non- 

 living. We may, if we like, take the living as our Norma, 

 and say to the Physicists, You must come to us for Laws, 

 you must account for the play of energies in universal nature 

 by referring them to Evolution, Descent, Adaptation. Or 

 we may take these words as true expressions of the mutual 

 relations between the phenomena and processes peculiar to 

 living beings, using for the explanation of the processes 

 themselves the same methods which we should employ if 

 we were engaged in the investigation of analogous pro- 

 cesses going on independently of life. Between these two 

 courses there seems to me to be no third alternative, unless 

 we suppose that there are two material Universes, one to 

 which the material of our bodies belongs, the other com- 

 prising everything that is not either plant or animal. 



The second reason is a practical one. We should have 

 to go back to the time which I have ventured to call pre- 

 scientific, when the world of life and organisation was sup- 

 posed to be governed exclusively by its own Laws. The 

 work of the past fifty years has been done on the opposite 

 principle, and has brought light and clearness where there 

 was before obscurity and confusion. All this progress we 

 should have to repudiate, but this would not be all. We 

 should have to forego the prospect of future advance. 

 Whereas by holding on our present course, gradually pro- 

 ceeding from the more simple to the more complex, from 

 the physical to the vital, we may confidently look forward 

 to extending our knowledge considerably beyond its present 

 limits. 



A no less brilliant writer than the one already referred 

 to, who is also no longer with us, asserted that mind was a 



