from each other in quality; that fire, for example, had a different quality or qualities from water; that sugar differed in quality from salt; that light differed in quality from sound; that wood differed in quality from stone and from iron, and so on. All these qualitative differences the Atomic theory abolished, or tended to abolish. It sought to reduce them all to the simplicity of mere quantitative differences. The atoms were held to have no qualitative differences. They differed, as has been said, from each merely in shape, arrangement, and position (σχῆμα τάξις καὶ θέσις), perhaps also in magnitude and weight. And it was the different configuration and arrangements of these exceedingly minute particles which imparted to the different objects in the universe their apparently qualitative differences. The atoms of fire, for example, are the same as those which compose water, only their size, weight, shape, and arrangement are different, and hence arises what seems to be a qualitative difference in the objects which result from their combination. So of sugar, and salt, and flesh. Here the same elements are differently combined; and hence sugar and salt appear to differ in quality. So of light and sound. The ultimate particles of these two are the same; but their configuration and arrangement are different, and hence a qualitative difference seems to subsist between them. So of wood, and stone, and iron. In reality there are no qualitative differences among these things, but only differences arising from the shape,
