EVOLUTION AND DISSOLUTION. 293 



or the constituent portions of a mass differently placed with 

 respect to one another, is sure to be at the same time a 

 progress towards integration or towards disintegration — is 

 sure to have altered in some degree the total space occupied. 

 For when the parts have been moved relatively to one 

 another, the chances are infinity to one that their average 

 distances from the common centre of the aggregate are no 

 longer the same. Hence whatever be the special character 

 of the redistribution — be it that of superficial accretion or 

 detachment, be it that of general expansion or contraction, 

 be it that of re-arrangement, it is always an advance in 

 integration or disintegration. It is always this, though it 

 may at the same time be something further. 



§ 96. A general idea of these universal actions under 

 their simplest aspects having been obtained, we may now 

 consider them under certain relatively complex aspects. 

 Changes towards greater concentration or greater diffusion, 

 nearly always proceed after a manner much more involved 

 than that above described. Thus far we have supposed one 

 or other of the two opposite processes to go on alone — we 

 have supposed an aggregate to be either losing motion and 

 integrating or gaining motion and disintegrating. But 

 though it is true that every change furthers one or other of 

 these processes, it is not true that either process is ever 

 wholly unqualified by the other. For each aggregate is at 

 all times both gaining motion and losing motion. 



Every mass from a grain of sand to a planet, radiates 

 heat to other masses, and absorbs heat radiated by other 

 masses ; and in so far as it does the one it becomes integrated, 

 while in so far as it does the other it becomes disintegrated. 

 Ordinarily in inorganic objects this double process works 

 but unobtrusive effects. Only in a few cases, among which 

 that of a cloud is the most familiar, does the conflict 

 produce rapid and marked transformations. One of these 

 floating bodies of vapour expands and dissipates, if the 



