264 PHYSICAL SCIENCE IN THE MIDDLE AGES. 



inventiveness ; and show us, very instructively, how 

 the decay of art and of science alike accompany 

 this indistinctness of ideas which we are endea- 

 vouring to illustrate. 



4. Indistinctness of Ideas in Astronomy. 

 Returning to the sciences, it may be supposed, at 

 first sight, that, with regard to astronomy, we have 

 not the same ground for charging the stationary 

 period with indistinctness of ideas on that subject, 

 since they were able to acquire and verify, and, 

 in some measure, to apply, the doctrines previously 

 established. And, undoubtedly, it must be con- 

 fessed that men's notions of the relations of space 

 and number are never very indistinct. It appears 

 to be impossible for these chains of elementary 

 perception ever to be much entangled. The later 

 Greeks, the Arabians, and the earliest modern 

 astronomers, must have conceived the hypotheses 

 of the Ptolemaic system with tolerable complete- 

 ness. And yet, we may assert, that, during the 

 stationary period, men did not possess the notions, 

 even of space and number, in that vivid and vigor- 

 ous manner which enables them to discover new 

 truths. If they had perceived distinctly that the 

 astronomical theorist had merely to do with rela- 

 tive motions, they must have been led to see the 

 possibility, at least, of the Copernican system ; as 

 the Greeks, at an earlier period, had already per- 

 ceived it. We find no trace of this. Indeed the 

 mode in which the Arabian mathematicians pre- 



