Therefore everything in existence is, fundamentally, made out of two things. There are bodies and there is the void in which these bodies have their places and through which they move in different directions. For sensation which is common to everybody declares that body exists. And unless we hold fast to this original belief in sensation, we shall find that in matters beyond the reach of sensation we shall have no principle to which we can refer and by means of which we can arrive at rational conclusions. Next, if there were no such thing as space (which is what we mean by "the void") there would be nowhere in which the bodies could be situated and it would be quite impossible for them to move about in different directions. . . . There is nothing else — nothing which you could say was distinct both from body and from void and could be pronounced to be a third substance. For everything that is to exist must be something in itself; if it is capable of touching and being touched, however light and small the touch may be, it will, provided that it does exist, increase the quantity of body to some extent, whether great or small, and be an addition to the sum of things. If on the other hand it is intangible and unable to prevent any object in motion from passing through it at any point, then unquestionably it must be what we call the empty void. Then again, whatever is to exist in itself will either do something, or else must remain passive itself while other things act upon it, or else must be of the sort in which things can exist and actions can take place. But nothing can act or be acted upon without body and nothing can afford space except the void and the empty. Therefore apart from the void and bodies it is impossible for there to exist in the sum of things any residual third substance. Such a substance could never at any time come within the reach of our senses, nor could any man lay hold of it by any process of reasoning.
You will find that all things which we say exist are either properties or accidents of these two. A property is what is absolutely inseparable from the object so long as the object remains in existence; thus weight is a property of stone, heat of fire, liquidity of water, touch of all bodies, intangibility of the void. On the other hand, examples of what we may properly call accidents are slavery, poverty and riches, freedom, war, peace and all the other things which can be present or absent without disrupting the nature of whatever we are considering. . . .
Bodies can be divided into (i) the original atoms, (ii) compounds made up of these atoms. As for the original atoms, no power is able to destroy them. Their solid bodies will resist and outlast all assaults. And yet it seems hard to believe that there is anything in existence with such absolute solidity. Heaven's thunderbolt goes through the walls of houses; so does sound and the noise of voices. Iron becomes white-hot in fire, and stones often split apart when exposed to violent heat. By heat too the hardness of gold is first undermined and then dissolved, and the icy texture of bronze, conquered by flame, turns to liquid. Both warmth and penetrating cold ooze through silver; we have felt both of them when we hold the goblet in our hands and a draught of liquid is poured into it from above. Indeed it certainly appears that there is no solidity anywhere. Nevertheless, since true reason and the very nature of things force me to speak, I must ask for your attention until in a few verses I demonstrate the existence of things which have bodies that are absolutely solid and everlasting. These, in our teaching, are called the seeds of things and their first beginnings, out of which the whole sum of things in its present state has been formed.