2 MYSTICISM AND LOGIC 



Heraclitus, as every one knows, was a believer in 

 universal flux : time builds and destroys all things. 

 From the few fragments that remain, it is not easy to 

 discover how he arrived at his opinions, but there are 

 some sayings that strongly suggest scientific observation 

 as the source. 



" The things that can be seen, heard, and learned," he 

 says, " are what I prize the most." This is the language 

 of the empiricist, to whom observation is the sole guaran- 

 tee of truth. " The sun is new every day," is another 

 fragment ; and this opinion, in spite of its paradoxical 

 character, is obviously inspired by scientific reflection, 

 and no doubt seemed to him to obviate the difficulty of 

 understanding how the sun can work its way under- 

 ground from west to east during the night. Actual 

 observation must also have suggested to him his central 

 doctrine, that Fire is the one permanent substance, of 

 which all visible things are passing phases. In com- 

 bustion we see things change utterly, while their flame 

 and heat rise up into the air and vanish. 



" This world, which is the same for all," he says, " no 

 one of gods or men has made ; but it was ever, is now, 

 and ever shall be, an ever-living Fire, with measures 

 kindling, and measures going out." 



" The transformations of Fire are, first of all, sea ; and 

 half of the sea is earth, half whirlwind." 



This theory, though no longer one which science can 

 accept, is nevertheless scientific in spirit. Science, too, 

 might have inspired the famous saying to which Plato 

 alludes : " You cannot step twice into the same rivers ; 

 for fresh waters are ever flowing in upon you." But we 

 find also another statement among the extant fragments : 

 " We step and do not step into the same rivers ; we are 

 and are not." 



