178 ON THE ORIGIN OF THE PLANETARY SYSTEM. 



matter itself. It seems as if Groethe had an idea of 

 this when he makes the earth-spirit speak of himself 

 as the representative of natural force. 



In the currents of life, in the tempests of motion, 

 In the fervour of art, in the fire, in the storm, 



Hither and thither, 



Over and under, 



Wend I and wander. 



Birth and the grave, 



Limitless ocean, 



Where the restless wave 



Undulates ever 



Under and over, 



Their seething strife 



Heaving and weaving 



The changes of life. 

 At the whirling loom of time unawed, 

 I work the living mantle of God. 



Let us return to the special question which con- 

 cerns us here : Whence does the sun derive this enor- 

 mous store of force which it sends out ? 



On earth the processes of combustion are the 

 most abundant source of heat. Does the sun's heat 

 originate in a process of this kind? To this question 

 we can reply with a complete and decided negative, 

 for we now know that the sun contains the terrestrial 

 elements with which we are acquainted. I^et us select 

 from among them the two, which, for the smallest mass, 

 produce the greatest amount of heat when they com- 

 bine ; let us assume that the sun consists of hydrogen 

 and oxygen, mixed in the proportion in which they 

 r oiild unite to form water. The mass of the sun is 



