

ii ARISTOTLE ON FINITUDE OF WORLD 185 



and he replies, " it is infinite man, or infinite ass, or 

 infinite tree, each and all, since in the infinite all 

 particular things are one and the same/' 



The arguments we have traced are: (i) What 

 appears to be a limit to our senses always proves to be 

 imaginary, when we are able to test it, therefore we may 

 infer that it is imaginary in other cases ; (2) the very 

 notion of space, implying that it has neither form nor 

 place, means that it is infinite, limitless ; (3) we cannot 

 imagine a portion of space than which there is not 

 another greater, and so ad infinitum : but reality cannot 

 fall short of thought, therefore space is infinite. The 

 arguments of Aristotle against the infinity of the world Aristotle. 

 are taken up in detail in the second book of the De 

 Immenso. As the controversy, however important at the 

 time, has lost much of its interest for us, we need only 

 give a brief sketch of its main lines. The first argu- 

 ment was drawn from the assumption of an ultimate 

 sphere or primum mobile which moved about the earth as i. The/, 

 a centre. 2 It was clear that if the universe were infinite the 

 radii of this sphere would be infinitely prolonged, and 

 therefore the termini of any two given radii at an infinite 

 distance one from another. The motion of the sphere 

 would thus be inconceivable, for it would require 

 infinite time in which to pass from one point to another. 

 The answer of Bruno was that the universe as a whole 

 was not moveable at all, nor had it any centre ; only its 

 parts were moved and each of these had its own relative 

 and finite centre. The apparent motion of the sphere 

 was due to the real movement of the earth about its 

 axis. A similar answer was given to the argument The 



_ .. . elements. 



from the movements of bodies according to their 



1 Cf. Infinite, Lag. 322. i ff. for the argument. 



2 Bk. ii. ch. 2. ; cf. Infinito, Dial, v., Lag. 387. 



