12 THEORY OF THE FIRMAMENT. 



The fourth is, that all heavenly motions are distributed 

 through perfect circles ; which is a very cumbrous doctrine, 

 and has produced to us those monsters of eccentric curves 

 and epicycles ; whereas, however, had they consulted nature, 

 a regulated and uniform motion belongs to a perfect circle ; 

 but a motion, regulated indeed, but of different forms, such 

 as is found in many of the heavenly bodies, is the property 

 of other lines ; and with good reason Gilbert ridicules these, 

 because it is not likely that nature should have formed 

 wheels, which, for example, contain one or two miles in 

 circumference, in order that a ball of a finger s breadth 

 should be sustained : for of so little magnitude does the 

 body of a planet appear to be, compared with those circles 

 round which they pretend it is to be carried. 



The fifth is, that stars are parts of their sphere, as if 

 fixed therein by a nail. But this is most clearly a reverie 

 of those who deal in mathematics, not in nature, and are 

 so stupidly intent on the motion of bodies, that they en 

 tirely forget their substances. For that fastening is a par 

 ticular disposition of compact and consistent things, which 

 have firm cohesions, because of the pressures of the parts. 

 But it is utterly to be unlocked for, if it be applied to soft 

 or liquid substances. 



The sixth is that a star is a denser part of its sphere of 

 action ; for the stars are not only not parts, but neither are 

 they denser ; for they are not homogeneous with ether, and 

 that in degree only, but they are entirely heterogeneous, 

 and differ in substance ; and, besides, that substance, as to 

 density, is rarer, and more expanded than an ethereal one. 

 Over and above these there are many other conceits of 

 equal whimsicality; but these shall suffice for the subject 

 now under discussion. Again, these observations have 

 been made on the fanciful dicta of philosophy respecting 

 the heavens. But as to what respects the hypotheses of 

 astronomers, the refutation of them is generally without 

 any use; for neither are they asserted for truths, nor is 

 it impossible that, although they may vary and be con 

 tradictory in themselves, the phenomena should equally 

 be preserved and harmonize. Therefore, if you please, 

 between astronomy and philosophy, as if linked together 

 by an expedient and legitimate bond, be so circumspect a 

 mediator, that, on the one hand, astronomy may have her 

 previous hypotheses, which are best adapted to t expedite 

 calculations ; on the other, philosophy, such as approach 

 nearest to the truth of nature ; and so that the hypotheses 



