THE STORY-BOOK OF SCIENCE 



"And what do the four columns rest on, in their 

 turn? 7 ' 



' 'They rest on four white elephants. " 



"And the white elephants?" 



"They rest on four monstrous turtles. " 



"And the turtles I" 



* * Well, they swim in an ocean of milk. ' ' 



"And the ocean of milk?" 



"The legend says nothing about that, and it is 

 right to be silent. It would have been better not 

 to imagine all these various supports, resting one 

 on another, to hold the earth up. Suppose a pedes- 

 tal for the earth, then a second to uphold the first, 

 then a third, fourth, thousandth, if you like; it is 

 only postponing the question without answering it, 

 since finally, after having erected all the supports 

 imaginable, one must ask what will the last one rest 

 on. Perhaps you are thinking of the vault of the 

 heavens, which might well sustain the earth; but 

 know that this vault has no reality, that it is nothing 

 but an appearance caused by the air. Besides, thou- 

 sands of travelers have gone over the earth in every 

 direction, and nowhere have they seen either a sus- 

 pending chain or a pedestal of any kind. Every- 

 where they see only what is to be seen here. The 

 earth is isolated in space ; it swims in a void without 

 any support, just as do the moon and the sun." 



"But, then, why does n't it fall?" persisted Jules. 



"To fall, my little friend, is to rush earthward as 

 a stone does when raised in the hand and then left 

 to itself. How can the large ball rush to the earth, 



