IN NATURAL HISTORY. 313 



we cannot, in these cases, have so certain know- 

 ledge as we have of that which falls under our own 

 immediate observation, we have it as well established 

 as it can be by testimony. 



Cases such as that of the entire destruction of a 

 whole tribe, or species, of organic beings, do not 

 come even within the scope of testimony ; for his- 

 tory, being chiefly confined to the transactions of 

 men, and, generally speaking, even to a very limited 

 number of them, is silent with regard to the others, 

 even^n those instances which from the circumstan- 

 tial evidence we would be led to conclude had fallen 

 within the period over which it extends. In the 

 instance above quoted, there is every circumstantial 

 proof that the castle was built while the neighbour- 

 ing ground was wood and copse, and not peat-bog : 

 and the appearance of a castle with hewn revetments 

 and grouted walls bespeaks a degree of civilization 

 higher than that of any people altogether without a 

 history. But still there is not a single trace remain- 

 ing ; and that is at once a proof that those people 

 neglected the observation of nature, and of the loss 

 which we now sustain from its being so neglected 

 and that, not at one remote point merely, but at 

 all points. We have, for instance, the history of 

 the inhabitants of London, the more remarkable 

 buildings, and even the very streets, but where is 

 the history of the Thames and its valley 1 ? and yet 

 both may, indeed must, have undergone many 

 changes since the Roman legions first appeared on 

 the banks of the river. So also every river and 

 river's valley must have changed ; and those changes 

 must have had an influence on the weather, the cli- 

 mate, the seasons, the plants, the animals, and the 

 whole natural history of the country, in so far as 

 that can be affected by the changes of time, or those 

 of any thing that time changes. But for the want 

 of observation and record, the whole of that is lost. 

 We are consequently ignorant of the great natural 

 Dd 



