ASTRONOMICAL HISTORY. 



of their increase, though they be only of one kind. For as 

 respects the ancient stars, no one in the memory of all ages 

 has remarked the rise of any of them (except what the 

 ancient Arcadians fabled about the moon), and none of 

 them has been missed: whereas, with respect to those 

 which are regarded as comets, but of a stellar form and 

 motion, and in fact as new stars, we have both witnessed, 

 and learned from the ancients, their appearances, and dis 

 appearances : while to some they seemed, in the latter, to 

 waste away ; to others, to be taken up (as if they had de 

 scended towards us in their circuits, and afterwards returned 

 to the higher regions) ; to others, to be gradually rarified 

 and dissipated in ether. But the whole of our inquiry 

 respecting the new stars we refer to that place in which 

 we speak of comets. 



Another question remains, that with respect to the ga 

 laxy, whether the galaxy be a collection of the smallest of 

 the stars, or a combined body and region of the ether of 

 an intermediate substance between that of the ether and 

 the stars. For that theory about exhalations has itself 

 now long exhaled, not without fixing a brand on Aristotle s 

 genius, who had the audacity to put forth such a figment, 

 fastening upon a thing so invariable and fixed an evanes 

 cent and fluctuating character. But an end of this ques 

 tion as proposed by us seems to be easily attainable, if we 

 are to give credit to the accounts of Galileo, who has ar 

 ranged that confused luminous appearance into numbered 

 and mapped constellations. For that the galaxy does not 

 prevent the visibility of those stars which are found within 

 its limits, is not enough to settle the question, nor to incline 

 the matter either way. It only refutes, perhaps, the notion 

 that the galaxy is placed lower than the part of ether con 

 taining the stars ; for if this were the case, and the conti 

 nuous body had also some depth of itself, it is consistent 

 with reason to suppose that our vision would be prevented. 

 And if it were placed at the same altitude as the stars 

 which are visible in it, there is no reason why stars should 

 not be scattered about in the galaxy itself, not less than in 

 the rest of the ether. Thus we have treated of this ques 

 tion. These six questions then refer to the substance of 

 the heavenly bodies ; what, namely, is the substance of 

 heaven in general, what of the interstellar air, what of the 

 galaxy, and what of the stars themselves, whether com 

 pared with one another, or with our fire, or with their own 

 essence ? 



