The Boundless Universe

But since I have taught that the most solid bodies of matter fly about forever, unconquered through all time, come now, let us unfold whether there is some limit to their sum or none; and likewise let us look into the void we have found—the room or space in which all things are carried on—and see whether the whole of it is bounded, or stretches out immeasurable and fathomless in its depth.

The whole of what exists, then, is bounded in no direction; for if it were, it would have to have an outermost edge. Yet nothing, it seems, can have an edge unless there is something beyond to bound it, so that there is a point past which our sense can follow it no farther. Now, since we must admit that there is nothing outside the sum of things, it has no edge, and so it lacks all end and measure. Nor does it matter in which region of it you take your stand: whatever place anyone occupies, he leaves the universe stretching boundless just as far in every direction.

Suppose, besides, that all existing space were bounded, and someone ran forward to its farthest shores and, standing at the very edge, hurled a flying spear. Would you have that spear, flung with mighty strength, fly on to where it was aimed and travel far, or do you think something could stop it and stand in its way? You must admit one or the other and choose. Yet either choice cuts off your escape and forces you to grant that the universe stretches out without end. For whether there is something to check the spear and keep it from reaching its mark and coming to rest at the limit, or whether it flies on beyond, it did not set out from the end. In this way I will press you: wherever you set the farthest shores, I will ask, "What, then, becomes of the spear?" It will turn out that no limit can stand anywhere, and that the room for flight will always prolong the flight.

Again, if all the space of the whole universe were shut in on every side by fixed shores and were bounded, then the whole store of matter, drawn by its solid weights, would long ago have flowed together from every side to the bottom, and nothing could go on beneath the canopy of the sky; there would be no sky at all, no light of the sun, since all matter would lie heaped together, having sunk down through infinite time. But as it is, no rest is given to the bodies of the first-beginnings, because there is no bottom at all where they could flow together, as it were, and settle. All things are always carried on in ceaseless motion in every part, and swift bodies of matter are supplied from beneath, out of the infinite.

Lastly, before our very eyes one thing is seen to bound another: air walls off the hills, and the mountains the air; land bounds the sea, and the sea in turn bounds every land. But the universe has nothing outside to bound it. Such, then, is the nature of place, the space of the deep, that the bright thunderbolts could not run through it in their course, though they glided on through endless time, nor by all their going leave less of the way still to go. So far and wide does a vast room lie open for things, with no bounds on any side, in every direction.

Moreover, nature herself forbids the sum of things to set a limit for itself, since she compels body to be bounded by void, and void in turn by body, so that by this alternation she makes the whole infinite; or else, if one of the two did not bound the other, that one, in its simple nature, would still stretch out without measure. Were it otherwise, neither sea nor land nor the shining precincts of the sky, nor the race of mortals, nor the holy bodies of the gods could hold their place for one brief hour; for the store of matter, driven apart from its union, would be carried, dissolved, through the great void—or rather, it would never have come together to create anything at all, since, once scattered, it could never have been driven together.

For certainly the first-beginnings of things did not settle each into its order by design or with shrewd intelligence, nor did they bargain over what motions each would produce. But because, many and changed in many ways, they have been driven by blows and tossed through the universe from infinite time, by trying every kind of motion and union they come at last into such arrangements as those from which this sum of things is formed and stands. And this world, preserved through many great years once it had been cast into fitting motions, brings it about that the rivers replenish the greedy sea with the generous waves of their streams, that the earth, warmed by the sun's heat, renews its young, that the race of living creatures springs up and flourishes, and that the gliding fires of the ether live on. This they could by no means do unless a store of matter could rise up from the infinite, from which things are accustomed to make good in time whatever they have lost.

For just as the nature of living creatures, deprived of food, wastes away and loses its substance, so all things must dissolve as soon as matter, turned aside from its path in any way, fails to be supplied. Nor can blows from outside hold together, on every side, the whole of any world that has been gathered. They can indeed strike it often and hold back a part of it, until others come and the sum can be made up; yet at times they are forced to rebound, and in doing so they grant the first-beginnings of things room and time for flight, so that they can be carried free from the union. That is why, again and again, many bodies must keep rising up; and even so that the blows themselves may not fail, there must be an infinite force of matter on every side.

I have shown that the most solid bodies of matter fly about forever, unbroken through all time. Now let us work out whether their total has a limit or not. Let us also examine the void we have found to exist—the room or space in which everything happens—and see whether all of it is bounded or whether it stretches out without measure and without bottom.

All that exists has no boundary in any direction. If it did, it would need an outer edge. But nothing can have an edge unless there is something beyond it that marks where it ends—a point past which our senses cannot follow it. We have to admit that there is nothing outside the whole of things, so the whole has no edge. It has no end and no measure. And it makes no difference where in it you stand. Whatever spot anyone takes, the universe still stretches out endlessly, just as far in every direction.

Now suppose all of space were bounded. Suppose someone ran out to its very edge, stood at the last boundary, and threw a spear. Would you say that the spear, thrown hard, goes where it was aimed and flies on into the distance? Or do you think something could block it and stop it? You have to pick one of these. But either answer leaves you no way out and forces you to admit that the universe goes on without end. If something blocks the spear and keeps it from reaching its target and coming to rest at the edge, then something lies beyond the edge. If the spear flies on outward, then it did not start from the edge. So I will keep after you. Wherever you put the outer edge, I will ask: "Then what happens to the spear?" The result is that no edge can exist anywhere, and there is always more room for the flight to go on.

Also, if all the space in the universe were closed in on every side and had fixed limits, all the matter in it would long ago have sunk to the bottom under its own weight, flowing in from every side. Nothing could happen under the sky. In fact there would be no sky and no sunlight, because all matter would lie in one heap at the bottom, having settled there over endless time. But as it is, the bodies of the first-beginnings never get to rest, because there is no bottom anywhere for them to collect in and settle on. Everything is always moving, everywhere, and fast-moving bodies of matter keep arriving from below, out of the infinite.

Finally, we can see with our own eyes that one thing marks the limit of another. Air separates the hills, and mountains separate the air. Land borders the sea, and the sea borders every land. But nothing outside borders the universe. Space is so vast that even lightning, racing along for all eternity, could not cross it, or bring the end of its journey any closer. That is how widely room for things lies open everywhere, with no limits in any direction.

Nature itself keeps the universe from setting a limit on itself. It makes body be bounded by void, and void be bounded by body, and by this alternation it makes the whole infinite. Or, if one of the two did not bound the other, that one on its own would still stretch out without measure. Otherwise the sea, the land, the bright regions of the sky, the human race, and the holy bodies of the gods could not last for even a short hour. The supply of matter would be knocked apart and carried off, scattered, through the great void. Or rather, it would never have come together to make anything at all, because once scattered it could never have been gathered.

The first-beginnings of things certainly did not arrange themselves in order on purpose, by some clever plan, and they did not agree among themselves about what motions each would make. Instead, there are many of them, changed in many ways, and they have been knocked about by blows and driven through the universe for endless time. By trying every kind of motion and combination, they finally fall into arrangements like the ones that make up this world. Once the world was set into the right motions, it has been kept going for many long years. Because of that, rivers refill the hungry sea with their plentiful water, the earth, warmed by the sun, brings forth new growth, the race of living things grows and thrives, and the gliding fires of the sky stay alive. None of this could happen unless a supply of matter could keep rising out of the infinite, so that things can make up in time for what they lose.

Living creatures that go without food waste away and lose their bodies. In the same way, everything must fall apart as soon as the supply of matter is cut off, turned aside from its path in any way. And blows from outside cannot hold together every part of a world once it has formed. They can strike it again and again and hold part of it in place until more matter arrives and the total can be made up. But sometimes they are forced to bounce back, and that gives the first-beginnings room and time to escape and move away, free of the mass. So many bodies must keep rising up, again and again. And for the blows themselves to keep coming, there must be an infinite amount of matter on every side.