358 THE INTELLECTUAL RISE IN ELECTRICITY. 



motion grind one upon the other, producing spheres and 

 also filings or parings due to mutual abrasion of the poly- 

 gons at their angles. By this means, there comes into ex- 

 istence the transparent substance of the skies (ether), the 

 material of luminous bodies, such as the sun and fixed 

 stars, and the material of opaque bodies, such as the 

 planets. The motions of these parts are those of revolving 



DESCARTES. 1 



currents or vortices, wherein the luminous body is at the 

 center and the ether surrounds it. In the solar vortex the 

 planets are immersed, and with it are whirled around. 

 The similarity of Descartes' conception of a solar vortex 

 to Kepler's notion of the magnetic whirlpool surrounding 



1 Reduced fac simile of the frontispiece of his Principia Philosophies. 

 Amsterdam, 1692. 





