436 SKETCH TOWARDS A 



any further ; and it is not within my plan to speculate 

 beyond proofs, nor to state the prevailing opinions re- 

 specting successions, improvements, or whatever else, 

 in which geologists have indulged. There is no Evi- 

 dence : and if this is to he considered a needful portion 

 of a Theory of the Earth, I believe that it is for ever 

 likely to remain a blank. Whatever has been pro- 

 posed is fanciful, if not false : and, when pretending 

 to proof, resting on that negative evidence which is 

 nothing ; since too much must have been lost, to allow 

 of those conclusions which have been so wantonly or 

 ignorantly drawn. 



On this portion of the Theory of the Earth, it re- 

 mains to ask whether there was a new creation for each 

 condition, or whether it was uninterruptedly progres- 

 sive from the commencement. There seem to me to 

 be two geological arguments for extinctions and re- 

 newals : it is another enquiry whether these apply to 

 each condition here enumerated. The first is, that 

 we cannot conceive a general revolution from fresh 

 formations of igneous rocks, without a total destruc- 

 tion of all life ; and the other, that we find certain new 

 sets of strata commencing without the presence of or- 

 ganic remains, while these increase in the progress of 

 time. To apply these arguments is less easy : while I 

 admit of no third one, derived from the characters of 

 the remains, since it can have nothing to rest on but 

 the negative evidence which I have so often rejected, 

 and since every thing hitherto advanced on this sub- 

 ject is purely hypothetical. Admitting these argu- 

 ments, we ought, I think, to conclude, that the organic 

 creations of the two first inhabited globes were really 

 destroyed and renewed,, This is probably true of the 

 third also ; but at this point our doubts must com- 

 mence ; because it is here that it becomes uncertain 



