COSMIC PHILOSOPHY 



out taking into the account that specialized 

 group of terrestrial phenomena which we distin- 

 guish as organic. Here there have been two con- 

 ditions favourable to the retention of enough 

 motion to allow considerable secondary rear- 

 rangement of parts. In the first place the great 

 size of the earth has prevented it from parting 

 too rapidly with the heat generated during its 

 condensation ; and since the early formation of 

 a solid, poorly conducting crust, the loss from 

 radiation would seem to have been very grad- 

 ual. The importance of this circumstance may 

 best be appreciated by remembering the very 

 different career of the moon, as indicated in the 

 foregoing chapter. The disappearance of igne- 

 ous and aqueous agencies on the moon implies 

 the cessation of structural rearrangement there 

 at this early date ; * and when we sought for an 

 explanation of this state of things, we found an 

 adequate explanation in the rapid loss of heat 

 which the small size of the moon has entailed. 

 It is not likely, therefore, that the moon can 

 ever have been the theatre of a geologic and 

 organic development so rich and varied as that 

 which the earth has witnessed. 2 



1 This statement must be taken, however, with some qual- 

 ification. See above, pp. 284, 285. 



2 An example of the too hasty kind of inference which is 

 often drawn in discussing the question of life upon other plan- 

 ets may be found in a recent lucid and suggestive pamphlet 



3H 



