138 THE WORLD MACHINE 



argument to prove that the air is material, that it has weight ; 

 they had, in brief, very much the same idea about it as we have 

 now. They probably had no air-pump to make a vacuum ; 

 but they could observe the tremendous force of the winds when 

 this same air was set in motion. From the gentlest zephyr 

 to the wild tornado which could throw down the walls of houses, 

 uproot trees, even cut them off sharply as if they had been 

 smitten with an axe, there was no gap. One graded into 

 another. It was very clear that the air, in its way, is just as 

 real a substance as water, even though in so many ways it 

 escapes our senses. 



Over the illusions of sense, indeed, Democritus seems to 

 have spent a deal of time. It is told of him that he used to go 

 out into his garden, where he could be quite unobserved, and 

 spend hours upon hours " testing his senses." It is fine mental 

 exercise. Nothing can open the gateways of the mind more 

 surely to the great thoughts that came to his. 



Perhaps it was from the suggestion of the motes in the sun- 

 beam that Democritus rose to the conception of particles not 

 merely indivisible but invisible as well, and far beyond the 

 palpation of the senses. It is only in their aggregations that 

 they became sensible, yet of them all things are made. Their 

 aggregations may be as minute as the particles of air, the motes 

 of the beam ; they may be worlds and suns. For Democritus 

 space was infinite ; through space the atoms rained downwards 

 for ever in an infinite stream ; they fall by reason of their 

 weight, the heavier particles falling faster than the small ones. 

 This gives rise to clusters or clumps of atoms, these in turn to 

 others, until you have the solid stuffs which our hands may 

 grasp, our eyes may see. 



Democritus pictured these atoms as indestructible as well. 

 Two thousand years before Lavoisier he clearly saw that the 

 forms of matter change, but none is lost. In the transmutation 

 of the atoms we have the varied shapes of things ; but as to 

 the elements of matter itself, there is no annihilation, no 

 creation. Nothing comes from nothing. That was a dogma, 

 doubtless, that was very old before Democritus came upon the 

 scene, but no one that we know of in that ancient day taught 

 it so clearly, or.iollowed it so far. 



He had, then, the first of the two great " laws " which our 

 modern time regards as fundamental to all experimental science. 



