176 ASTRONOMICAL HISTORY. 



the stars, on account of the smallness of their size, com 

 pared to the magnitude of the stars. Besides the body of 

 the moon itself, except in the part in which it receives 

 light, does not alter the appearance of the sky, so that 

 were that light annihilated, so large a body would entirely 

 escape our view. But, on the contrary, it is clearly appa 

 rent, from those bulky bodies, which by their mass and 

 magnitude overcome the effect of distance, and on account 

 of their luminous or sparkling substance forcibly strike 

 our view, that surprising changes and anomalies happen in 

 the heaven. And that is perceived in the higher order of 

 comets, I mean those which assume the appearance of a 

 star without the coma, and which are not only proved by 

 the doctrine of parallaxes to be placed above the moon, 

 but bear a certain and unchangeable relation of position to 

 the fixed stars, and retain their stations without being 

 erratic; of such our age has seen more than one, first in 

 Cassiopeea, and afterwards not long ago in Ophiuchus. 

 And as to this kind of regularity, which is seen in such 

 comets arising from their following the motion of some 

 star (which was the opinion of Aristotle, who asserted that 

 there was a like relation of a comet to the motion of a par 

 ticular star, and of the galaxy to that of the stars col 

 lectively, both positions being false), that has now been 

 long exploded, not without a stigma on the genius of Aris 

 totle, who in his airy speculations had the presumption to 

 invent such things. Nor in fact does this change in the 

 heavenly bodies with respect to such new stars, obtain only 

 in those stars which appear to be of a vanishing nature, 

 but also of those which remain in their place. For in 

 the instance of the new star of Hipparchus, of the ap 

 pearance of which mention is made among the ancients, 

 there is none made of its disappearance ; a new star has 

 lately become visible in the breast of Cygnus, which has 

 now continued for twelve entire years, exceeding the dura 

 tion of a comet, which it has been held to be, by a consider 

 able period, and not yet lessened in disk, or threatening to 

 disappear. Nor again, is it properly and invariably true, 

 that the old stars are not subject to change, but only the 

 stars of later Epiphany, in which it is not to be wondered 

 if change takes place, since their very production and 

 commencement is not immemorial. For passing over that 

 fable of the Arcadians with respect to the first appearance 

 of the moon, in which they boast that they are of greater 

 antiquity than that planet, there are not wanting in history 



