'THEORY of the EARTH. 297 



OUR objecl is to know the time which had elapfed fince the 

 foundation of the prefent continent had been laid at the bot- 

 tom of the ocean, to the prefent moment in which we fpecu- 

 late on thefe operations. The fpace is long ; the data for the 

 calculations are, perhaps, deficient : No matter ; fo far as we 

 know our error, or the deficiency in our operation, we proceed 

 in fcience, and (hall conclude in reafon. It is not given to man 

 to know what things are truly in themfelves, but only what 

 thofe things are in his thought. We feek not to know the pre- 

 cife meafure of any thing ; we only underftand the limits of a 

 thing, in knowing what it is not, either on the one fide or the 

 other. 



WE are investigating the age of the prefent earth, from the 

 beginning of that body which was in the bottom of the fea, to 

 the perfection of its nature, which we confider as in the mo- 

 ment of our exiftence ; and we have neceffarily another sera, 

 which is collateral, or correfpondent, in the progrefs of thofe 

 natural events. This is the time required, in the natural ope- 

 rations of this globe, for the deftrudlion of a former earth j 

 an earth equally perfect with the prefent, and an earth equally 

 productive of growing plants and living animals. Now, it 

 muft appear, that, if we had a meafure for the one of thofe 

 correfponding operations, we would have an equal knowledge of 

 the other. 



THE formation of a future earth being in the bottom of the 

 ocean, at depths unfathomable to man, and in regions far be- 

 yond the reach of his obfervation, here is a part of the pro- 

 cefs which cannot be taken as a principle in forming an efti- 

 mate of the whole. But, in the definition of the prefent 

 earth, we have a procefs that is performed within the limits of 

 our obfervation ; therefore, in knowing the meafure of this 

 operation, we fhall find the means of calculating what had 

 patted on a former occafion, as well as what will happen in the 



P p compofition 



