ASTRONOMICAL HISTORY. 173 



habitually disconnected for so many ages, are one and the 

 same thing, and concrete in one body of science. 



Therefore we propose it as our first question, Whether 

 or not there is a diversity between the substance of the 

 heavenly bodies and that of this lower orb ? For the pre 

 mature and dogmatical doctrine of Aristotle has created 

 for us only an imaginary heaven, formed of a certain fifth 

 essence without change and also without heat. And 

 waiving for the present any discussion respecting the four 

 elements which this quintessence takes for granted, it was 

 certainly a piece of great temerity to annihilate all affinity 

 between the elementary substances as they are called, and 

 the heavenly bodies; when two of the elements, namely 

 air and fire, agree so well with the star and the ether ; but 

 it was the custom of that great man to abuse his genius, 

 create work for himself, and prefer the obscure. Not, how 

 ever, that there is any doubt that the regions situated 

 above and beneath the moon, along with the bodies com 

 prehended within the same limits and space, differ in many 

 important particulars. J\ T or again is this more certain than 

 that in the bodies of each region there exist many tenden 

 cies, affections, and motions common to both ; so that, 

 preserving unbroken the unity of nature, we ought rather 

 to discriminate than to pluck them forcibly asunder. And 

 as regards one part of the supposed discrepancy, namely, 

 that the celestial bodies are imagined to be eternal, the 

 sublunary perishable, that doctrine seems to be a fallacy 

 either way, as neither that eternity which they fancy is 

 true of heaven, nor that mutability of earth. Indeed to 

 one who justly weighs the matter, a judgment ought by no 

 means to be formed from those things which are visible to 

 us, since none of the objects which meet the human eye 

 are dug or cast up from a greater depth than about three 

 miles at most, which is as nothing compared to the dia 

 meter of the earth. Therefore nothing hinders that the 

 interior part of the earth may be endowed with a like eter 

 nity to heaven itself. For if the earth were subject to 

 changes in its womb, it is impossible that the results of 

 those changes should not produce greater calamities on the 

 surface of it which we tread, than we see taking place. 

 For of those changes which present themselves conspicu 

 ously to us here in the direction of the surface of the 

 earth, there is generally some visible and apparent cause 

 acting from above, such as tempests, rains, heat, and the 

 like; so that the earth of itself, and of its own virtue, 



