CONCEPT OF AN ATOMIC UNIVERSE 137 



world without end. We may pursue the operation to the 

 mental extinction of infinitude, and the mind will set no bar. 



But, on the other hand, it is equally unimaginable that any 

 number of parts or particles, infinitely small, can make up an 

 actual tangible something, when brought together. We may, if 

 we like, try to conceive of an infinitude of infinitesimals ; but a 

 collocation of these for every grain of salt or sugar is a trifle 

 wearisome, to say nothing of the fact that it eludes clear mental 

 presentation. Common-sense folk will hardly waste good; time 

 over such cobwebs, though it is curious to recall that this seemed 

 the most satisfactory view to such an eminently practical and 

 concrete mind as Faraday's. 



For the ordinary affairs of life, our bodies, so alive to pain, 

 the foods we eat, so needful, the liquids we drink, the gases 

 without which we cannot for a moment survive, the houses 

 we live in, the stones we tumble over, seem very real. So do 

 the folk, disagreeable and agreeable, that we find about us ; 

 the earth we tread, the hills we climb. How account for their 

 existence ? Democritus chose the least tenuous of the two 

 unthinkables : the infinitely divisible and the finitely indivisible 

 that is, the latter. He called these ultimate particles by a 

 name which described them just as he thought of them, as 

 a-tomic or undivisible that is, atoms. 



Doubtless in this he had many predecessors. Some such 

 idea must have drifted across the mind of many a thinker many 

 hundreds of years before. It is a conception that must soon 

 unfold in any reflecting mind. If a chink in a wall lets through 

 a beam of sunlight into a darkened room, seen sidewise the 

 air is full of dancing particles. It is merely an illusion of the 

 senses, then, to think of the room as empty. It is full of 

 dancing motes. If we are very careful to leave a room un- 

 disturbed, by-and-by on objects in the room a fine dust gathers, 

 and the motes will have almost disappeared from the sun's 

 gleam. 



Evidently, then, these motes are not air ; but float in the 

 air. And if they can float in the air, even as other bodies float 

 in water, then the air is equally real, conceivably also made up 

 of parts or atoms. It is perfectly clear that so Democritus 

 thought of it. In the pages of Lucretius, in which the thoughts 

 of Democritus, filtered through the writings of Epicurus, re- 

 appear after three or four centuries, there is a vivid and striking 



