318 LAUGEL'S PROBLEMS OF NATURE AND LIFE. 



latter fact one of the greatest discoveries of modern 

 science we gain a certain unity for the problem, in 

 the conception of a single Power which, indestructible 

 in itself, acts in different modes and degrees throughout 

 the material universe the source of all motion and 

 change in the greatest and in the most minute pheno- 

 mena of nature. But this at best is a cloudy concep- 

 tion, insusceptible of any direct proof, and incapable of 

 being moulded into a definition. The abstract idea 

 looms before us, but escapes before we can grasp it. 



Nor can we shelter our ignorance under any of the 

 various terms used by philosophers to designate this 

 power Swards, eVepyeia, vis viva, vis mortua, 

 dynamic energy, potential energy, ' lebendige Krafte,' 

 or whatever else the diversities or impotence of lan- 

 guage have suggested. These phrases, even were 

 they congruous, do little more than repeat the pro- 

 blem in new words. We are still dealing with 

 what is unperceived by any of our senses itself, for 

 aught we can tell, immaterial and known only as the 

 cause of sensible changes in the matter around us. 

 Nor do we gain much here by seeking, as some have 

 done, to conceive of force as a mere expression of the 

 intestine changes which matter itself, in its atomical 

 parts, is ever undergoing, and which are in perpetual 

 translation and interchange from one material form to 

 another. This is shifting the difficulty without solving 

 it. Whence come these motions and innumerable in- 

 terchanges in matter ? What is the power initiating 

 and propagating them ? To say that it is one inherent 

 in matter itself thickens rather than dispels the dark- 



