INFLUENCE ON RECENT SCIENCE 83 



space, and that it consists of atoms either in a vacuum 

 or in a non-material medium, is the property known as 

 expansion and contraction. As an illustration, he in- 

 stances a sponge, which changes size but not character 

 when its pores are filled with water. Here we have a 

 change of size from the change of position of sponge- 

 matter, the two kinds being of the same essence. So 

 the change of volume of any body is due to a change 

 of position of matter-substance produced by a change 

 of space-substance, which also are essentially the same 

 and differ only in accidental qualities. 



Furthermore, since we cannot imagine a space so 

 great that there cannot be a greater, or so small that 

 it cannot be divided, then as matter is essentially the 

 same as space, it too must be indefinitely great in ex- 

 tent and indefinitely divisible. 



This is a very complicated way of getting back to 

 one's starting point. He says first, that substance is 

 extension and then that space is extension, but since 

 extension is everywhere and space is nowhere vacuous, 

 a body is a body. 



Having discussed the nature of matter in general, 

 he then finds that diversity in matter and also its dif- 

 ferentiation from space can consist only in variations 

 of position and motion of small parts of space which 

 are themselves exactly similar. As corollaries to this 

 definition, it follows that there can be neither absolute 

 position nor absolute motion. To determine the posi- 



