On the Nature of Things (De Rerum Natura)

315

The iron referring to a plowshare imperceptibly decreases in the fields, and we behold the stone-paved streets worn down by the feet of the multitude. The brass statues too at the gates show their right hands to be wasted by the touch of the numerous passers-by who greet them. These things then we see are lessened, after they are thus worn down; but what bodies depart at any given time, nature has jealously shut out the means of seeing.
320

Lastly, the bodies which time and nature add to things by little and little, constraining them to grow in due measure, no exertion of the eyesight can behold. And so too, wherever things grow old by age and decay, and when rocks hanging over the sea are eaten away by the fine salt spray, you cannot see what they lose at any given moment. Nature, therefore, works by unseen bodies.
329

And yet all things are not on all sides jammed together and kept in by body: there is also inane void in things. To have learned this will be good for you on many accounts; it will not suffer you to wander in doubt and be to seek in the sum of things and (distrustful of our words.) If there were not void, things could not move at all; for that which is the property of body, to let and hinder, would be present to all things at all times.