34 CLASSICS OF MODERN SCIENCE 

 part of the surface of the earth are revolved along with the whole 

 globe about its axis from west to east and by this revolution the im- 

 movable stars of the east are disclosed to us one after the other, and 

 those of the west are obscured, so the stars are not passing over us, 

 but the vertical point is moving through the fixed stars. 



You say that by this marvelous hypothesis may be explained satis- 

 factorily all the phenomena of the first motion and the spherical 

 theory. Just so, and that is the scope of this section, to demonstrate 

 in fact what has been suggested in words. 



How do you expect to be able to prove this absurd hypothesis, and 

 by what arguments? It is possible to demonstrate that this first 

 motion results from the revolution of the earth about its axis, while 

 the heavenly bodies are at rest (as far as this first motion is concerned), 

 by seven kinds of arguments: i) from the subject of the motion; 

 2) from the velocity of the motion; 3) from the equableness of the 

 motion ; 4) from the cause of the motion, or the moving principle ; 

 5) from the motive instruments, that is, the axis and the poles; 6) 

 from the object of the first motion; and 7) from the indications or 

 results. 



Demonstrate it then from the subject of the motion. Nature does 

 not seek difficult means when she can use simple ones. Now, by the 

 rotation of the earth, a very small body, about its axis, toward the east, 

 the same thing is accomplished as by the rotation of the immense uni- 

 verse about its axis toward the west. Just as it is more likely that a 

 man's head turns in the auditorium than that the auditorium is turned 

 about his head, so it is more credible that the earth is rotating from 

 west to east, than that the rest of the machine of the universe is re- 

 volved from east to west, since in both cases the same thing results. 



If the first motion is in the heavenly bodies, then they are subject 

 to two motions, one common to the whole universe, the other par- 

 ticular to each sphere; but it is much more probable that the two 

 motions should be distinct in regard to their subjects, so that the 

 second set of motions, which is multifold, should belong to each sphere, 

 and the first, which is single, should belong to the single body of the 

 earth, and to it alone. 



Why cannot the whole machinery of the universe be moved? The 

 universe is either infinite or finite. Suppose it to be the former, 

 according to the opinion of William Gilbert, who thinks that the 



