12 SCIENCE AND IMMORTALITY 



that they are infinite both in number and in their 

 forms, and that the differences between things are 

 due to the elements of which they are composed, and 

 to the position and arrangement of these elements." 



Theophrastus, in his opinions, gives Leucippus' 

 views rather more fully : " He assumed innumer- 

 able and ever-moving elements, namely, the atoms. 

 And he made their forms infinite in number, since 

 there was no reason why they should be of one 

 kind rather than another, and because he saw that 

 there was unceasing becoming and change in 

 things. He held further that what is, is no more 

 real than what is not^ and that both are alike causes 

 of the things that come into being ; for he laid 

 down that the substance of the atoms was compact 

 and full, and he called them what is, while they 

 moved in the void which he called what is not, but 

 affirmed to be just as real as what is'' How like 

 this is the modern view of ether and its vibrations ! 



Leucippus was probably the originator of the 

 atomic theory, but only these fragmentary accounts 

 of sayings of his are extant, and the theory is usu- 

 ally associated with the name of Democritus, who 

 propounded his views at considerable length. His 

 fundamental propositions are given by Mendeleef 

 as follows : — 



"(i) Nothing can proceed from nothing, no- 

 thing that exists (and hence matter) can disappear 



