98 TUB OCEAN. [Book III. 



in the course of time it will cease to exist : presuming, 

 of course, that it is only reasonable to suppose that 

 something immaterial pre-existed from which it had 

 its origin, and that when it has run its course and 

 ceased to exist, something immaterial evolved from 

 it will exist after it. We are, however, concerned only 

 with the forces brought into play by the evanescence 

 of matter, and not with the immaterialities which 

 pre-existed, or into which it is in process of trans- 

 mutation ; and these forces, termed evanescence, 

 tending to control matter in a constant series of 

 evolutions through its existence, causing constant 

 change of form and place, bring into play the force 

 of gravitation in consequence of the action of vis- 

 inertias, by virtue of which matter tends to preserve 

 its existence, or hold itself together, and continue 

 where and what it is.^ 



' See Chapter XIX. of The New Princijyles of Natural Philo- 

 sophy, ' Is force inherent in matter 1 And is matter evanescent 

 or indestructible 1 ' 



