EXCURSIONS OF AN EVOLUTIONIST 



sent quite clear away from the sphere of action 

 of the surrounding molecules. But, notwith- 

 standing that, all molecules in a liquid are con- 

 stantly changing their places, and it is for that 

 reason that diffusion takes place in the liquid. 

 ... In the case of a solid, quite a different 

 thing takes place. In a solid every molecule has 

 a place which it keeps ; that is to say, it is not 

 at rest any more than a molecule of a liquid or 

 a gas, but it has a certain mean position which 

 it is always vibrating about and keeping fairly 

 near to, and it is kept from losing that position 

 by the action of the surrounding molecules." l 



Such scientific exposition as this is as beauti- 

 ful as poetry. In reading it one feels how the 

 glory and beauty of Nature are immeasurably 

 enhanced for the philosopher who can thus with 

 inward vision distinctly grasp objects and rela- 

 tions too subtile for the eye of sense in any wise 

 to discern. 



This same remarkable lucidity is exhibited 

 by Clifford in the treatment of metaphysical 

 problems. In some respects the most striking 

 discussion in the present volume is contained 

 in the essay on " The Nature of Things-in- 

 themselves," where some of the latest sugges- 

 tions of anti-materialistic philosophy are very 

 forcibly presented. Starting from the impreg- 

 nable Berkeleian position that the material 

 1 Vol. i. p. 194. 

 298 



