CHAPTER XXX 



THE STRUCTURE OF THE UNIVERSE 



LOOKING up of a summer's night into the firmament with its 

 countless silvered points of light, there seems little enough to 

 suggest any idea of arrangement or order. For aught that the 

 unaided eye might know, they might be merely incandescent 

 bulbs stuck at random in the ceiling of the sky. For all we 

 can see, they wheel together about the pivot star. 



In the beginnings of astronomy there seemed as little order 

 or arrangement *in the movements of the errant stars, the 

 wanderers, the planets. They went in a zigzag aimlessness 

 across the heavens, marching forwards and backwards in a 

 bizarre fashion that was at first unaccountable enough. It 

 was long centuries before men were able, from this apparent 

 tangle, to reach the idea that the planets move in circles. When 

 at last it was made clear that they do, the simplest arrange- 

 ment that could be imagined for the unmoving stars was to 

 suppose they were attached to a crystal sphere which enclosed 

 space. This, as we know, is what the ancients did. 



Among the ancients there were a few, like Democritus, who 

 could rise to more sublime conceptions ; there were very few. 

 But when in our modern time the planetary arrangement had 

 at last been solidly grounded, the question of the spacing of 

 the stars came back again. 



Our human knowledge has often advanced through recourse 

 to analogy. Vaguely we have come to perceive that the order 

 of phenomena is relatively simple. In our ignorance we imagine 

 more than is needful. The explanation of one narrow group 

 of facts leads often to the enchainment of many. When, in 

 the seventeenth century, the remoteness of the stars, or, in 

 other words, the detachment of the solar system, had become 

 clear, it was natural to think of our planetary arrangement as 

 a microcosm which might be the mirror of the macrocosm. 



It is hard to say to whom the idea came first. The imper- 



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