The Evolution Hypothesis. 



Now, however recondite what Mr. Spencer de- 

 scribes as the " developed ideas of matter and motion " 

 may be, it is matter and motion with which we are 

 still dealing, and nothing but matter and motion. The 

 play of atoms internal to the most minute molecule, 

 is as truly an instance of matter and motion as the 

 revolution of the earth round the sun. Differences in 

 size do not constitute differences of kind. " The play 

 of forces is essentially the same in principle through- 

 out the whole region explored by our intelligence " ; * 

 whether it be the movement of masses or " the oscilla- 

 tions of the molecules of either " the principle is the 

 same ; and it matters little whether we call the 

 doctrine "dynamic" or "mechanical." Let the evolu- 

 tionist extend as widely as he will the conception of 

 dynamic law, by imagining a series of systems reaching 

 towards infinity in their minuteness, subtil ty, and 

 complexity ; let him give freest play in the invention 

 of composition of causes adequate to the production of 

 any conceivable result ; yet, however far the fancy 

 travels from the visible, however marvellous that 

 other world revealed in its worders to the scientific 

 imagination, the materials of which it is built up are 

 still the same force manifested in the atom and its 

 vibrations, matter and motion, and the law of their 

 continuous redistribution shaping and ruling all 



t First Principles, 91. 



