r PROLEGOMENA 3 



jo hare gone and to go on for ever, is but a 

 leetiiu;- phase uf her infinite variety; merely the 

 ast of the series of changes which the earth's sur- 

 face has undergone in the course of the millions of 

 fears of its existence. Turn back a square foot of 

 :he thin turf, and the solid foundation of the land, 

 exposed in cliffs of chalk five hundred feet high on 

 :he adjacent shore, yields full assurance of a time 

 >vhen the sea covered the site of the " everlasting 

 lills " ; and when the vegetation of what land lay 

 learest, was asjlifferent from the present Flora of 

 ;he Sussex downs, as that of Central Africa now is. 1 

 No less certain is it that, between the time during 

 vhich the chalk was formed and that at which the 

 mginal turf came into existence, thousands of 

 :enturies elapsed, in the course of which, the state 

 )f nature of the ages during which the chalk was 

 leposited, passed into that which now is, by 

 changes so slow that, in the coming and going of 

 ;lie generations of men, had such witnessed them, 

 :he contemporary conditions would have seemed 

 ;o be unchanging and unchangeable. 



But it is also certain that, before the deposition 

 )f the chalk, a vastly longer period had elapsed, 

 throughout which it is easy to follow the traces 

 )f the same process of ceaseless modification and 

 jf the internecine struggle for existence of living 

 .hings ; and that even when we can get no further 



1 See "On apiece of Chalk" hi the preceding volume of these 

 Essays (vol. viii. p. 1). 



B 2 



