320 POPULAR SCIENCE MONTHLY. 



of heavy bodies towards the earth's center other men are dropping 

 balls into holes bored entirely through the globe and these balls are 

 falling to the earth's midmost point — 



That point to which from every part is dragged all heavy substance, 

 as Virgil explains to Dante in the thirty-fourth canto of the Inferno. 

 The cosmogony of Dante in the Divina Commedia was accepted for 

 centuries by Eoman Catholics, as Milton's in the Paradise Lost has 

 been adopted by protestants. For Dante the globe of the earth was 

 the center of the world. It was surrounded by nine transparent 

 spheres moved by angels. There was a crystal sphere for the moon, 

 and others for Mercury, Venus, the sun, Mars, Jupiter, Saturn and 

 the fixed stars, and beyond them the Prinium Mobile — nine in all. 

 Beyond the outer sphere was the Empyrean — here God sate. Below 

 the earth is hell and here its god — Lucifer — reigned over bad angels. 

 All the discord in the world came from them, even its storms, hail 

 and lightning. The spheres of Eudoxus served as a base to Dante's 

 system, which was adapted, with a poet's license, to a poet's use.* 



In the De Ccelo, Aristotle lays down certain fundamental principles : 

 The things of which the world is made are all solid bodies, and all 

 have, therefore, three dimensions. The simple elements of nature 

 must also have simple motions. So, indeed, fire and air have their 

 natural motions upwards, water and earth, downwards, both in straight 

 lines. But besides these motions there is also a circular motion, not 

 natural to these elements, although it is a much more complete motion 

 than the rectilinear. For the circle is, in itself, a complete line, which 

 a straight line is not: There must, therefore, be certain things to 

 which complete circular motion is natural: It follows that there 

 must be a certain sort of bodies very dilferent from the four elementary 

 bodies, bodies that are more godlike, that must therefore stand above 

 them: This finer essence was later named by the commentators 

 *Quinta Essentia' — our quintessence. The heavenly bodies are formed 

 of this; they are spheres endowed with life and activity. 



The question of the revolution of the earth in an orbit round the 

 sun is discussed by Aristotle, and he rejects the idea for the reason 

 that such a motion would necessarily produce a corresponding altera- 

 tion in the place of each and every fixed star. The objection was per- 

 fectly valid. If the stars were only a little farther from us than 

 Saturn, as Aristotle believed, a motion of the earth in an orbit would 

 cause each star to move in an apparent parallactic orbit, a miniature 

 copy of that of the earth. No such alteration of place was observable. 

 Hence, said he, the earth did not move. Even the nearest stars are, 



* The upper regions of Paradise contained the narrow-minded monks of the 

 middle age as well as the great saints. The wisest and most virtuous heathens, 

 like Virgil, were in Limho — which, it has been remarked, contained the ' best 

 society.' Outcasts from all religionsj and sinners of all sorts, were in Hell. 



