38 CLASSICS OF MODERN SCIENCE 



public testimony of my undying love; may the recollection of their 

 eloquence aid me in setting down for posterity the spoken discussions. 



SECOND DAY 



Salviati: We departed yesterday so often and so far from the 

 direct path of our discussion, that I can scarcely return to the right 

 point and proceed without your help. 



Sagredo: I find it quite intelligible that you are somewhat at a 

 loss, since you have had your head so full of both the things already 

 brought forward and things still to be discussed. I, however, who as 

 merely a listener have in mind only the things already discussed, may 

 I hope set our investigation straight by a brief summary of what has 

 been gone over. So, if my memory fails not, the chief result of our 

 yesterday's conversation was that we tested thoroughly which of 

 the two theories was the more probable and better grounded; that 

 according to which the substance of the heavenly bodies is un- 

 producible, indestructible, unchangeable, intangible, in brief not sub- 

 ject to any variation aside from change of location, and so presents 

 a fifth element which is entirely distinct from our elementary, 

 producible, destructible, changeable bodies ; or the other view, ac- 

 cording to which an incongruity between parts of the universe is 

 rejected, our earth rather enjoys the same privileges as the rest of the 

 constituent bodies of the universe, in a word, is a freely moving ball 

 just as the moon, Jupiter, Venus, or any other planet. Finally we 

 noticed the many similarities in particular between the earth and the 

 moon, and of course with the moon more than any other planet 

 because of the closer and more definite knowledge which we possess 

 of it by reason of its less distance. Since we agreed that this second 

 opinion possessed the greater probability, the logical consequence, it 

 seems to me, is that we should investigate the question whether we 

 should hold the world inmovable, as has been formerly believed in 

 general, or movable as some ancient philosophers believed and as 

 some recent ones suppose: and if movable, how its movement could 

 have been produced. 



Salv. : Let us begin our discussion with the admission that what- 

 ever sort of motion may be ascribed the earth, we, as its inhabitants. 



