ON GEOLOGICAL TIME. IT 



celebrated theorem of the stability of the planetary 

 motions was announced. That theorem was taken 

 up somewhat rashly, and supposed to imply more 

 than it really did with reference to the permanence 

 of the solar system. It was probably it which 

 Playfair had in his mind when he wrote that 

 celebrated and often-quoted passage " How often 

 " these vicissitudes of decay and renovation have 

 " been repeated is not for us to determine ; they 

 " constitute a series of which, as the author of 

 " this theory has remarked, we neither see the 

 " beginning nor the end ; a circumstance that 

 " accords well with what is known concerning other 

 " parts of the economy of the world. In the 

 " continuation of the different species of animals 

 " and vegetables that inhabit the earth, we discern 

 " neither a beginning nor an end ; in the planetary 

 " motions where geometry has carried the eye so 

 " far both into the future and the past, we discover 

 " no mark either of the commencement or the 

 " termination of the present order. It is unreason- 

 " able, indeed, to suppose that such marks should 

 " anywhere exist. The Author of nature has not 



