PLURALITY OF WORLDS. 31 



has become, either by a designed method or by con- 

 jectured causes of change, the abode of the higher 

 animals and of man, why may not the other planets 

 have passed through the same or analogous conditions 

 and attained the same result ? Both questions are of 

 presumption only. The latter, I think, has greater 

 weight in the argument ; and we cannot reasonably 

 admit any dogma of ancient theology or inference from 

 Scriptural language, which some have brought into it, 

 to annul the conclusion so obtained. 



Taking the whole problem in its simplest form, it 

 will be seen as one never to be solved by absolute 

 proof, but admitting of strong presumptive evidence, 

 which is likely to become still stronger with increased 

 knowledge of the physical conditions of the planets 

 themselves. The track of recent discovery has lain 

 in this direction, and no limit can yet be assigned to its 

 further pursuit. 



