GREEK SCIENCE IN EARLY ATTIC PERIOD 



and that water is dark, when viewed under proper 

 conditions as at the bottom of a well. That idea 

 contains the germ of the Clazomenaean philosopher's 

 conception of the nature of matter. Indeed, it is not 

 unlikely that this theory of matter grew out of his 

 observation of the changing forms of water. He seems 

 clearly to have grasped the idea that snow on the one 

 hand, and vapor on the other, are of the same in- 

 timate substance as the water from which they are 

 derived and into which they may be again transformed. 

 The fact that steam and snow can be changed back 

 into water, and by simple manipulation cannot be 

 changed into any other substance, finds, as we now be- 

 lieve, its true explanation in the fact that the molecular 

 structure, as we phrase it that is to say, the ultimate 

 particle of which water is composed, is not changed, 

 and this is precisely the explanation which Anaxagoras 

 gave of the same phenomena. For him the unit par- 

 ticle of water constituted an elementary body, un- 

 created, unchangeable, indestructible. This particle, 

 in association with like particles, constitutes the sub- 

 stance which we call water. The same particle in 

 association with particles unlike itself, might produce 

 totally different substances as, for example, when 

 water is taken up by the roots of a plant and becomes, 

 seemingly, a part of the substance of the plant. But 

 whatever the changed association, so Anaxagoras 

 reasoned, the ultimate particle of water remains a par- 

 ticle of water still. And what was true of water was 

 true also, so he conceived, of every other substance. 

 Gold, silver, iron, earth, and the various vegetables 

 and animal tissues in short, each and every one of 



155 



