54 GALILEO AND HIS JUDGES. 



(the Earth), turning round on itself, would produce 

 the same effect. He argues also that if you believe 

 in this motion of the celestial sphere, you must 

 suppose the planets to be moving in two opposite 

 directions at the same time, the diurnal one from 

 east to west, and the annual one from west to east 

 using the word annual in its extended sense, as 

 applied to the periodical revolutions of all the planets. 

 To this Simplicio makes the sapient answer that 

 Aristotle proves that circular motions are not con- 

 trary to each other ; upon which the third inter- 

 locutor, Sagredo, asks him whether when two knights 

 meet one another in the open field, or two fleets at 

 sea in the latter case sinking each other such 

 motions can be called contrary? This Simplicio is 

 obliged to admit ; he uses, however, another argument, 

 which did not seem so absurd in the then existing 

 state of science, namely, that there may be another 

 sphere beyond that of the stars, and itself starless, 

 to which belongs the property of the diurnal revo- 

 lution, and that this sphere may carry along with it 

 the inferior spheres, these latter participating in its 

 movement. Ideas such as these were part of the 

 pre-telescopic notions of astronomy. Simplicio's 

 argument is in reply to some powerful reasons drawn 

 from the motions of the planets, the nearer revolving 

 in a shorter, and the more remote in a longer period ; 

 it being extremely unlikely that they would be all 

 whirled round the Earth in one day; and also from 

 considerations connected with the stars. 



