EVOLUTION AND DISSOLUTION. 295 



are dwindling, and even in cases where different parts are 

 differently exposed to external sources of motion so that 

 some are expanding while others are contracting, 'the truth 

 still holds. For the chances are infinity to one against 

 these opposite changes balancing one another; and if they 

 do not balance one another, the aggregate as a whole is 

 integrating or disintegrating. 



Everywhere and to the last, therefore, the change at any 

 moment going on forms a part of one or other of the two 

 processes. While the general history of every aggregate is 

 definable as a change from a diffused imperceptible state to 

 a concentrated perceptible state, and again to a diffused im- 

 perceptible state; every detail of the history is definable as 

 a part of either the one change or the other. This, then, 

 must be that universal law of redistribution of matter and 

 motion, which serves at once to unify the seemingly diverse 

 groups of changes, as well as the entire course of each group. 



§ 97. The processes thus everywhere in antagonism, and 

 everywhere gaining now a temporary and now a more or 

 less permanent triumph the one over the other, we call Evo- 

 lution and Dissolution. Evolution under its simplest and 

 most general aspect is the integration of matter and con- 

 comitant dissipation of motion ; while Dissolution is the ab- 

 sorption of motion and concomitant disintegration of mat- 

 ter. 



These titles are by no means all that is desirable; or 

 rather we may say that while the last answers its purpose 

 tolerably well, the first is open to grave objections. Evolu- 

 tion has other meanings, some of which are incongruous 

 with, and some even directly opposed to, the meaning here 

 given to it. The evolution of a gas is literally an absorp- 

 tion of motion and disintegration of matter, which is exactly 

 the reverse of that which we here call Evolution — is that 

 which we here call Dissolution. As ordinarily understood, 

 to evolve is to unfold, to open and expand, to throw out, to 



