MATTER AND FORCE, IN PHYSICAL PHENOMENA. 39 



broken or restored ? Or must we, as stated above, 

 bring in some cause, extraneous to matter itself, as 

 originating those atomic motions which we characterise 

 as the phenomena of heat ? To go to the great foun- 

 tain of heat in the sun, is but to shift the question a 

 step higher. And it is not a mere verbal question, 

 since we cannot construct a theory of heat without 

 recognising, not solely the modes of motion of matter, 

 but also the existence of forces on which these motions 

 depend. It might almost seem here as if reason got 

 into a trap of its own making. We call in powers 

 from without, to which matter is subordinate, though 

 necessary for their manifestation ; and invoking these 

 powers, we are left with the problem of their nature 

 unsolved. 



This illustration presents fresh difficulties when we 

 come to the phenomena of latent heat, and propound 

 the view, now generally adopted, that heat, as a force, 

 imbibed originally from the sun by vegetable life on 

 the earth, and following the conversion of the latter 

 into coal, has been stored up latently for untold ages in 

 a mineral form, to be developed in the furnaces of our 

 own day. We cannot disprove this, or bring other 

 more conceivable solution of this great natural pro- 

 blem. But when we speak of heat as a force consist- 

 ing integrally of certain atomic motions in bodies, 

 which force may be pent up for ages within these 

 atoms, ever ready for extrication, we are boun to 

 look fairly at the abstruse conceptions these things in- 

 volve ; if indeed they can be truly understood in any 

 other sense than as a method of expressing phenomena. 



