THE FABRIC OF MATTER ii 



matter by condensation and rarefaction, when he 

 taught that its fundamental form proceeded intact 

 from each successive variation, the thought must 

 plainly have dawned on him that minute impercep- 

 tible particles were there at work, now coming 

 closer together, and now departing from one an- 

 other. Again, when Heraclitus proclaimed his 

 doctrine of the ceaseless transformation of things, 

 and declared the uninjured existence of an in- 

 dividual object to be a mere delusion brought about 

 by the constant accession of fresh particles in the 

 place of those that had been severed, he was obvi- 

 ously assuming the presence of invisible particles 

 of matter as well as of their invisible movements. 

 And finally, when Anaxagoras complained of the 

 ' weakness ' of our senses, when he combined in 

 every corporeal structure an infinite number of 

 ' seeds ' or of the minutest primary particles, and 

 made the appearance of the structure depend on 

 the predominance of one sort of those particles, he 

 was stating, in unambiguous words, the very 

 doctrine which inference alone enables us to 

 attribute to his two predecessors." 



The atomic theory was, however, only implied 

 by these philosophers, and it was left to Leucippus 

 and Democritus explicitly to formulate it. Aristotle 

 states : " Democritus and Leucippus say that all 

 things are composed of indivisible bodies, and 



