170 ASTRONOMICAL HISTORY. 



berless scintillas in the ether between the fixed stars, (for 

 which other sufficiently unmeaning reasons are given), the 

 starry essence seems to be more diffused and spread out 

 continuously. But of these points we shall say more in 

 discussing those questions, which we presently propose to 

 consider, respecting the substance of the stars and the 

 interstellar ether. For what we now say relates only to 

 questions respecting the connexion of the system. 



A fifth question remains concerning the distribution of 

 the parts of the system, or the order of the heavenly bodies. 

 And granting that there is not a system but only scattered 

 globes, or granting that there is a system the centre of 

 which is the sun, or even allowing the astronomers to go 

 in quest of some new system, still there remains equally 

 this inquiry : What planet is nearer or more distant from 

 any other planet ? and in like manner what planet is at 

 a greater or less distance from the earth, or even from 

 the sun ? Now if the system of the ancients is admitted, 

 there seems no reason why we should attach great import 

 ance to any new inquiry concerning the four higher hea 

 vens, namely, those of the fixed stars, of Saturn, Jupiter, 

 and Mars. For their position and order are testified by the 

 suffrage of all antiquity, and by the absence of any contra 

 dictory phenomenon ; their modes of revolving also, whence 

 is derived our principal evidence of the relative heights of 

 the heavenly bodies, are adapted to this structure, and no 

 where interfere with it. But as to the Sun, Venus, Mer 

 cury, and the Moon, even on the principles of the old sys 

 tem, there was some doubt among the ancients; and among 

 the moderns it is still a question, with respect to Venus 

 and Mercury, which planet is higher than the other? For 

 in favour of the superior height of Venus this reason offers 

 itself, that it moves somewhat more slowly ; and of Mer 

 cury, that it is fixed at a nearer distance from the sun, 

 whence one should naturally maintain that it ought to be 

 placed next the sun in height. But, as to the moon, no one 

 ever had any doubt that its place was next the earth, 

 though there was a difference of opinion with regard to its 

 approaches to the sun. Nor ought one question relating 

 to the arrangement of the system to escape a serious in 

 quirer into the subject, which is this, whether the planets 

 alternately pass over and pass below one another ? which 

 seems to be authenticated in the case of Venus by ela 

 borate demonstrations of the fact that it is found sometimes 

 placed below the sun, sometimes above it. And doubtless 



