On the Nature of the Universe (Oxford World’s Classics) Page 9

  Or when you see the fleet come surging out

  And spreading far and wide across the sea,

  These things excite and thrill your mind, and drive

  Religion’s dread away, and fears of death

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  Leave your heart empty then, from care set free.

  But if we see that all this is ludicrous,

  And that in truth men’s cares and haunting fears

  Reck nothing of clash of arms or brutal missiles

  And boldly walk with kings and potentates,

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  Nor stand in awe of the bright sheen of gold

  Or brilliant splendour of a purple robe,

  How can you doubt that reason has this power,

  Reason alone? Our lives in very truth

  Are but an endless labour in the dark.

  For we, like children frightened of the dark,

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  Are sometimes frightened in the light—of things

  No more to be feared than fears that in the dark

  Distress a child, thinking they may come true.

  Therefore this terror and darkness of the mind

  Not by the sun’s rays, nor the bright shafts of day,

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  Must be dispersed, as is most necessary,

  But by the face of nature and her laws.

  Come, listen now, and I’ll explain the motions

  By which the generative bodies of matter

  Beget the various things and, once begotten,

  Dissolve them, and by what force they are driven to do this,

  And what power of movement through the mighty void

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  Is given them. Do you now mark my words.

  Matter, for sure, is not one solid mass

  Close packed together. We see that everything

  Diminishes, and through the long lapse of time

  We note that all things seem to melt away

  As years and age withdraw them from our sight.

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  And yet the sum of things stays unimpaired.

  This is because when particles are shed

  From a thing they diminish it as they leave it,

  And then increase the object that they come to.

  They make the one grow old, the other flourish,

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  But do not linger there. The sum of things

  Is thus forever renewed, and mortals live

  By mutual interchange one from another.

  Some races increase, others fade away,

  And in short space the breeds of living creatures

  Change, and like runners pass on the torch of life.

  Now if you think that atoms can be at rest

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  And can by resting beget new movements in things,

  You are lost, and wander very far from truth.

  For since the atoms wander through the void,

  All must be driven either by their own weight

  Or by some chance blow from another atom.

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  For often when, as they move, they meet and clash,

  They leap apart at once in different directions.

  No wonder, since they are extremely hard

  And solid, and there is nothing behind to stop them.

  To see more clearly that all particles of matter

  Are constantly being tossed about, remember

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  That there is no bottom to the universe,

  That primal atoms have nowhere to rest,

  Since space is without end or any limit.

  And I have shown by many words, and proved

  By surest reasoning that it extends

  Boundless in all directions everywhere.

  Since that stands true, no rest, we may be sure,

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  Is given to atoms in the void abyss

  But rather, as unceasing different

  Movements impel them, some, colliding, leap

  Great intervals apart, while others recoil

  Only a short distance from the impact.

  And those whose union being more closely packed

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  Leap back short distances after a collision,

  Being fast entangled by their own complex shapes,

  These constitute strong roots of stone and the brute bulk

  Of iron, and other objects of that kind.

  Of the rest, which wander further through the void,

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  A few leap far apart, and far recoil

  Over great intervals; these make for us

  Thin air, and make the shining light of sun.

  And many wander through the mighty void

  Rejected from all union with others,

  Unable anywhere to gain admittance

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  And bring their movements into harmony.

  An image and similitude of this

  Is always moving present to our eyes.

  Consider sunbeams. When the sun’s rays let in

  Pass through the darkness of a shuttered room,

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  You will see a multitude of tiny bodies

  All mingling in a multitude of ways

  Inside the sunbeam, moving in the void,

  Seeming to be engaged in endless strife,

  Battle, and warfare, troop attacking troop,

  And never a respite, harried constantly,

  With meetings and with partings everywhere.

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  From this you can imagine what it is

  For atoms to be tossed perpetually

  In endless motion through the mighty void.

  To some extent a small thing may afford

  An image of great things, a footprint of a concept.

  A further reason why you should give your mind

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  To bodies you see dancing in a sunbeam

  Is that their dancing shows that within matter

  Secret and hidden motions also lie.

  For many you will see are struck by blows

  Unseen, and changing course are driven back

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  Reversed on all sides, here, there, everywhere.

  These wandering movements, you may be sure, are caused

  In every case by atoms. Atoms first

  Move of themselves, next bodies that are formed

  In a small group and nearest to the force

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  Of the primal atoms are set moving by them,

  Driven by unseen blows from them; and they

  Attack in turn bodies a little larger.

  The movement thus ascends from primal atoms

  And comes out gradually up to our senses,

  And thus it is that those bodies also move

  That we can see in sunbeams, though the blows

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  That make them do it are invisible.

  Now, as to the speed with which the atoms move.

  This in a few words you may understand,

  Good Memmius, from what I now shall tell you.

  First, when dawn strews new light across the earth,

  And the birds flying through the pathless woods

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  In the soft air fill with their liquid notes,

  So varied and so sweet, the place below,

  We see then plain and manifest to all

  How suddenly the rising sun is wont

  To clothe the world and flood it with his light.

  But that heat and light serene the sun sends forth

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  Do not pass through empty void; and for this reason

  They are compelled to go more slowly, and

  To cleave their way as it were through waves of air.

  Nor do the particles of heat move separately,

  But in a mass all linked and massed together,

  So that at the same time they drag each other back

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  And meet external obstacles, and so move more slowly.


  But atoms, which are completely solid and single,

  When they pass through the empty void, and nothing

  Outside of them delays them, then they move

  As single units on the course on which they started.

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  Therefore they must be of surpassing speed

  And move much faster than the light of the sun,

  And cover a distance many times as great

  In the time the sun’s flash takes to cross the sky.

  [Text missing]

  And not to follow every single atom

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  To see in what way everything is done.

  Some people oppose this, being ignorant of matter,

  Believing that without the power of gods

  Nature could never match the needs of men

  So fitly as she does, so very closely,

  Changing the seasons and producing crops,

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  And all those other things which pleasure divine,

  The guide of life, leads mortals to enjoy,

  And through the arts of Venus coaxes them

  To breed, and propagate the generations,

  Lest the human race should perish. But when they imagine

  That gods have ordered all things for men’s sake,

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  In every way they have fallen far from truth.

  For even if I had no knowledge of atoms,

  This from the order of the heavens itself

  And many other facts I would dare assert—

  That in no way for us the power of gods

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  Fashioned the world and brought it into being.

  So great the faults of which it stands possessed.

  This, Memmius, I will make clear to you later.

  Now I’ll complete my account of the motion of atoms.

  This is the place, I think, to make the point

  That no material thing can by its own power

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  Ever be lifted up, or travel upwards.

  Do not let the atoms that make flame deceive you.

  For trees and shining crops spring into birth

  Upwards and grow and make their increase upwards,

  Though all weights by themselves tend downwards.

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  And when fires leap up to the roofs of houses

  And with swift flame devour beams and timbers,

  We must not think that of their own accord

  They do this, without some force below to drive them.

  Blood in the same way, let out from our bodies,

  Spurts in a jet aloft and splashes gore.

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  Do you not see also the power with which water

  Spits out beams and timbers? We press them down,

  Deep down, many of us pushing all together

  With might and main, and the harder we push them down

  The more the water wants to spew them up,

  And throw them back again, so that more than half

  Emerges and shoots up above the surface.

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  And yet I think we have no doubt that all of them

  Left to themselves would move downwards through the void.

  The same thing must happen with flames. These under pressure

  Can shoot up into the air, although their weights,

  Left to themselves, must fight to drag them down.

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  And the nocturnal torches of the sky

  Flying aloft, you see how in their wake

  Long trails of flame they draw, wherever nature

  Has set them on their course across the heavens.

  And see how stars and meteors fall to earth.

  And the sun also from the height of heaven

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  Throws its heat out and sows the fields with light.

  So the sun’s heat also inclines towards the earth.

  Lightning you see through rainstorms flies aslant;

  Now here, now there, the fires burst through the clouds

  Headlong together; the flaming bolt falls to the earth.

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  Now here is another thing I want you to understand.

  While atoms move by their own weight straight down

  Through the empty void, at quite uncertain times

  And uncertain places they swerve slightly from their course.

  You might call it no more than a mere change of motion.

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  If this did not occur, then all of them

  Would fall like drops of rain down through the void.

  There would be no collisions, no impacts

  Of atoms upon atom, so that nature

  Would never have created anything.

  If anyone believes that heavier atoms

  Moving straight down more quickly through the void

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  Can fall on lighter atoms from above

  And by this means produce the varied impacts

  That can give rise to generative motions,

  He is lost, and strays far from the path of truth.

  For when things fall through water or thin air,

  They must gain speed according to their weights;

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  For water’s mass and air’s thin nature cannot

  Slow down the pace of all things equally

  But must give way more quickly to the heavier.

  But, by contrast, nowhere at any time

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  Can empty void make resistance to anything,

  But as its nature demands it must give way.

  Therefore through the calm and quiet void

  All things must travel at an equal speed

  Though with unequal weight. The heavier

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  Will never have the power to fall upon

  The lighter from above, nor by themselves

  Beget impacts that make the varied mix

  Of movements by which nature fashions things.

  Therefore again and again I say that atoms must

  Swerve slightly, just the very least—no more—

  Or we shall find ourselves imagining

  A sideways movement, which the facts refute.

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  For it is plain and manifest that weights

  When falling from above, left to themselves,

  So far as meets the eye cannot move sideways.

  But whose eye can perceive that nothing swerves

  Ever so slightly from its straight course down?

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  Again, if movement always is connected,

  New motions coming from old in order fixed,

  If atoms never swerve and make beginning

  Of motions that can break the bonds of fate,

  And foil the infinite chain of cause and effect,

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  What is the origin of this free will

  Possessed by living creatures throughout the earth?

  Whence comes, I say, this will-power wrested from the fates

  Whereby we each proceed where pleasure leads,

  Swerving our course at no fixed time or place

  But where the bidding of our hearts directs?

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  For beyond doubt the power of the will

  Originates these things and gives them birth

  And from the will movements flow through the limbs.

  Consider racehorses. The starting gates

  Fly open, the horses are strong and keen to go,

  But can’t break out as fast as their minds would wish.

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  For all the mass of matter must be stirred

  Through the whole body, roused through every limb,

  Before it can follow the prompting of the mind.

  So you may see that heart begins the motion

  Then mind and will join in and drive it on

  Until it reaches all the body and limbs.

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  But let’s sup
pose another man has struck us

  A violent blow—he’s hit us really hard—

  And we move forward. That’s quite different.

  For all the matter then of all the body

  Clearly against our will is forced to move,

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  Until the will has reined limbs back again.

  Do you see the point? Though many men are driven

  By an external force, compelled to move

  Often in headlong rush against their will,

  Yet in our breasts there’s something that has the power

  To fight against this force and to resist it.

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  At its command at times the mass of matter

  Is forced to change direction in our limbs,

  Or, reined back on its way, it comes to rest.

  The same thing therefore we must admit in atoms:

  That in addition to their weights and impacts

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  There is another separate cause of motion,

  From which we get this innate power of ours,

  Since nothing ever can be produced from nothing.

  For it is weight that prevents all things being caused

  Simply by external impacts of other atoms.

  But that within the mind there’s no necessity

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  Controlling all its actions, all its movements,

  Enslaving it and forcing it to suffer—

  That the minute swerving of atoms causes

  In neither place nor time determinate.

  The mass of matter in the universe

  Was never more tightly packed than it is now,

  Nor ever set at wider intervals.

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  Nothing increases it or is taken away from it.

  Therefore the motions in which the primal atoms

  Are now have been the same for ages past,

  And in like manner they will move hereafter.

  And things which the ancient custom of the world

  Has brought to birth will always in like manner

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  Be brought to birth, and be and grow and flourish,

  So far as to each is given by Nature’s laws.

  No power can ever change the sum of things.

  No place exists to which any kind of matter

  Could escape from the universe, nor any place

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  From out of which some new force building up

  Could break into the universe, and change

  The nature of all things, and reverse their movements.

  And here’s a thing that need cause no surprise:

  That though all atoms are in ceaseless motion

  Their total seems to stand in total rest,

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  Except so far as individual objects

  Make movements by the movements of their bodies.

  For all the nature of the primal atoms

  Lies hidden far beneath our senses; therefore since

  You cannot see them, you cannot see their movements.