On the Nature of the Universe (Oxford World’s Classics) Read online

  Oft makes a noise in the great clouds on high.

  For the great mountains of the thunderclouds

  Are broken, pressed together by the wind,

  And crushed into a narrow space, and mixed with hail.

  Lightning occurs likewise when clouds colliding

  160

  Have struck out many seeds of fire, as stone

  Strikes stone or iron; then also light leaps out

  When stone is struck and scatters sparks of fire.

  Our ears receive the sound of thunder later

  Than our eyes see the lightning, for this reason;

  165

  Things always come more slowly to the ears

  Than to the eyes; as this example shows:

  If in the distance you observe a man

  Felling a tall tree with twin-bladed axe

  You see the stroke before the sound of it

  Reaches your ears; so also we see lightning

  170

  Before we hear the thunder, which is produced

  At the same time as the fire, and by the same cause,

  Born of the same collision of the clouds.

  Here is another way in which the clouds

  Bathe all the landscape in a fleeting light

  As the storm flashes with its quivering stroke.

  When wind has entered a cloud and whirling round

  175

  Has made the cloud condense around the hollow,

  As I explained before, it becomes hot

  With its own motion, as you see everything

  Grows burning hot with motion; leaden bullets

  Melt as they spin in a long flight through the air.

  So when the black cloud by the burning wind

  180

  Has been split up, the sudden violent pressure

  Makes it shoot out the seeds of heat, and these

  Produce the winking flashes of bright flame.

  Then the sound follows, coming to the ears

  More slowly than the light comes to our eyes.

  This happens, you must understand, when clouds are thick

  185

  And are piled high, one cloud upon another,

  By an amazing force. Don’t be misled

  Because observing from below we see

  More easily their wide expanse spread out

  Than the great mighty mass piled high above.

  Take note then, when you see clouds like mountains

  Carried before the winds across the sky,

  190

  Or when you see them on the mountain tops

  Piled high, one on another, pressing down

  And lying still, with all the winds at rest,

  Then you will recognize their mighty mass,

  And see great caverns fashioned in them

  195

  With beetling crags, and when a storm builds up

  Winds fill them, and imprisoned in the clouds

  They vent their indignation with a roar,

  And growl like angry beasts shut up in cages;

  This way and that they fill the clouds with din,

  And circle round and round trying to escape;

  200

  They roll the seeds of fire out of the clouds

  And mass them together, and in the hollow furnace

  They spin a circling flame, until at last

  They burst the cloud, and blaze into the sky.

  And also there’s another reason why

  That rushing golden gleam of liquid fire

  205

  Darts down to earth. It is that the clouds themselves

  Must contain very many seeds of fire.

  For when they are entirely free of moisture

  Mostly their colour is flaming and shining bright.

  Indeed from the sun’s light they must receive

  Many such seeds, so with good cause they blush

  210

  And pour out fires. These therefore, when the wind

  Has driven them together and compressed them,

  Squeeze out and then eject the seeds of fire

  Which make the colours of the lightning-flash.

  Lightning occurs also when in the sky

  The clouds are thinning out, for when the wind

  215

  Gently disperses them as they move on

  And dissolves them, then the seeds that make the lightning

  Must fall perforce; but then the lightning comes

  Noiseless, and without the hideous crash and terror.

  I now discuss the nature of thunderbolts.

  This the strokes show, and branding marks of heat,

  220

  And the holes breathing noxious fumes of sulphur.

  These are the marks of fire, not wind or rain.

  Besides, they often set roofs alight, and flame

  Gains quick dominion all inside the houses.

  This fire, my friend, the thinnest of all fires,

  225

  Nature has made of atoms so small and swift

  That nothing in the world can stand against it.

  The thunderbolt passes through walls of buildings

  As sounds and voices do, through stone, through bronze,

  And in an instant melts both bronze and gold.

  230

  And wine inside a vessel suddenly

  It makes evaporate, though the jar remains intact;

  Doubtless because, as the heat reaches it,

  It loosens the fabric of the earthenware

  And makes it porous, then entering the jar

  It quickly dissolves the atoms of wine and scatters them.

  235

  And this we see the sun can never do

  In an age, however strong its flashing heat.

  So much more mobile and more masterful

  Is the strong power of the thunderbolt.

  And now, how they are made and have such power

  That with a stroke they can split towers asunder,

  240

  Overturn houses, tear out beams and rafters,

  Move monuments of men, struck down and shattered,

  Rob human beings of life and slaughter cattle,

  And all else of this kind, by what strange power

  They work, I’ll tell, and delay you no more with promises.

  245

  We must believe that thunderbolts are made

  From thick clouds piled up high; they never strike

  From a clear sky or thin layer of cloud.

  The facts themselves make clear without a doubt

  That at a time of thunderstorms clouds mass together

  250

  Everywhere through the air, so that we think

  That all the darkness out of Acheron

  Has filled the mighty caverns of the sky.

  So dark, beneath the hideous night of cloud,

  The face of fear hangs over us above,

  When storm begins to forge the thunderbolts.

  255

  And very often too across the sea

  A black cloud falls, like pitch poured from the sky,

  Loaded with darkness from afar, and draws with it

  A black storm big with thunderbolts and blasts

  Filled to the brim itself with wind and fire,

  260

  So that on land also men shiver and seek shelter.

  From this we must infer that thunderstorms

  Stretch high above our heads. For so much blackness

  Could never overwhelm the earth unless

  A multitude of clouds piled high on clouds

  Built up above us, blotting out the sun.

  265

  Nor could there fall that torrent of the rain

  That makes the rivers flood and drowns the fields

  If ether were not full of clouds piled high.

  So everything is full of winds and fires

  And thunderclaps and lightning everywhere.

  270


  For indeed I have shown above that hollow clouds

  Must contain very many seeds of fire

  And must receive many from the sun’s hot rays.

  Therefore, when the same wind that has driven them

  Into one place together, has squeezed out

  Many seeds of fires, and in so doing itself

  275

  Has intermingled with the fire, the whirlwind

  Finds its way in, whirls round in the narrow space

  And in the hot furnace sharpens the thunderbolt.

  For the wind is kindled in two ways: by the heat

  280

  Of its own motion, and by contact with the fire.

  Next when the wind has reached a mighty heat

  And the strong impulse of the fire has entered,

  The thunderbolt, now as it were ripe, cleaves through

  The cloud by a sudden blow, and the heat, shot out,

  Lights all the place beneath with flashing flames.

  A deep roar follows, such that the vault of heaven

  285

  Seems to be sundered apart and falling on us.

  A violent tremor now assails the earth

  And murmurs roll about the sky; for then

  Almost the whole storm quivers with the shock

  And roars and crashes. Rain then, heavy and full,

  290

  Follows the shock, so that the whole ether

  Seems to be turned to rain, and teeming down

  Recalls again the universal Flood.

  So much the bursting cloud and raging wind

  Pour out when the sound flies from the flaming stroke.

  Sometimes also a powerful wind outside

  295

  Falls on a cloud pregnant with a ripe thunderbolt.

  It bursts it, and at once that fiery whirlwind falls

  Which we name thunderbolt in our native tongue.

  And this can strike in various directions,

  Depending on the impulse given to it.

  Sometimes also a wind that has no fire

  300

  Kindles nevertheless on its long flight through space;

  It loses on its course a number of bodies

  Too large to keep up with it through the air,

  And scrapes together from the air itself

  And carries with it other tiny bodies

  That mixed with it make fire as it flies,

  305

  In much the same way as a leaden bullet

  Often grows hot in flight, when throwing off

  The seeds of cold it catches fire in the air.

  Sometimes also a blow produces fire,

  When a cold wind launched without fire has struck.

  310

  Doubtless because when it has struck a violent blow

  Elements of heat can flow together

  Both from the wind itself and at the same time

  From the object receiving the blow, as fire flies out

  When stone is struck with iron, and the fire comes

  315

  No whit the less because the iron is cold.

  So also a thing must take fire from a thunderbolt

  If it be fit and suitable for flame.

  And no wind ever can be utterly

  And absolutely cold, if from above

  320

  So powerful a force has driven it.

  If it has not caught fire on its course,

  When it arrives it must be warm and mixed with heat.

  The speed and violent stroke of thunderbolts

  And the swift fall with which they cleave the sky

  Have this as their cause: a force within the clouds,

  325

  First everywhere aroused, accumulating

  Takes on a mighty energy of movement.

  Then when the cloud cannot hold the growing impetus

  The force explodes, and flies with wondrous speed

  Like missiles hurled from powerful catapults.

  Moreover, it consists of elements

  330

  Both small and smooth, so that it is not easy

  For anything to counter such a substance.

  For it flies in between and penetrates

  Through narrow passages, therefore few obstacles

  Can check it or delay it as it comes;

  And this is why it falls with flight so swift.

  Again, while all weights naturally possess

  335

  A downward momentum, when a blow is added

  The speed is doubled, and the first impulse

  Grows heavier, so that with greater speed and strength

  It shatters whatever delays it on its course.

  Again, the momentum of its lengthy flight

  340

  Must give it ever-growing speed, increasing

  As it falls, and this augments its mighty power

  And strengthens the blow. It causes all its atoms

  To move straight forward to a single point

  And throws them together as they flow into that path.

  345

  It may perhaps draw from the air itself

  In the course of its flight certain particles

  Which by their impact set its speed ablaze.

  It passes through things without harming them,

  And leaves many things intact after its transit,

  Because the fluid fire goes through the pores.

  And many it transfixes, when its atoms

  350

  Strike upon other atoms that form a joint.

  It readily dissolves bronze and in an instant

  Melts gold, because the atoms of which it is made

  Are small and smooth and therefore easily

  Make their way in, and having got in, at once

  Untie all knots and loosen every bond.

  355

  In autumn thunder shakes the house of heaven,

  Studded with shining stars, more often, and shakes the earth,

  And also when springtime opens with its flowers.

  For in the cold fires are few, and in the heat

  360

  The winds fail and clouds are not so thick.

  So when the season stands between the two

  Then all the various causes of thunderbolts

  Combine and flow together in the sky.

  For then the year’s rough straits mix cold and heat

  (And a cloud needs both to make a thunderbolt),

  365

  So discord comes and with a mighty tumult

  And fire and wind the heavens rage and swell.

  For the first time of heat is the last of cold,

  That is the spring. So battle must be joined

  With fray embroiled between things unalike.

  370

  And when the last heat mixed with early cold

  Comes round, to which we give the name of autumn,

  Here also bitter winter fights with summer.

  Therefore these must be named the straits of the year,

  And it’s no wonder if these seasons produce

  375

  Thunderbolts in abundance, and a whirling storm

  Forms in the sky, since war everywhere

  Rocks it on two fronts, on the one side flames

  And on the other wind and water mixed.

  Thus the true nature of the thunderbolt

  Can now be understood, and how it works;

  380

  Not by unrolling scrolls of Tuscan charms

  To search in vain the hidden minds of gods

  And ask them whence the flying fire has come

  Or to what other quarter of the sky

  It went, and in what way it penetrated

  Through walls of buildings, and having worked its will

  385

  Inside, made its way out again, or ask what harm

  The stroke of a thunderbolt from heaven can do.

  If Jupiter and other gods, my friend,


  Shake with appalling din the realms of heaven,

  And shoot their fire where each one wants to aim,

  Why do they not arrange that when a man

  390

  Is guilty of some abominable crime

  He’s struck, and from his breast transfixed breathes out

  Hot flames, a bitter lesson to mankind?

  Why is a man of conscience free from stain

  Engulfed in flames, all innocent, suddenly

  Seized by a fiery whirlwind from the sky?

  395

  Why do they waste their pains shooting at deserts?

  Or are they merely practising their aim

  And strengthening their muscles? Why do they allow

  The Father’s bolt to be blunted on the ground?

  Why does he allow this himself, and not keep it

  For his enemies? And why does Jupiter

  Never when the sky is cloudless everywhere

  400

  Launch bolts upon the earth and sound his thunder?

  Or does he wait until the clouds have formed

  And then himself descend down into them

  To aim his weapon from a shorter range?

  What is his object when he strikes the sea?

  Has he some grudge against the waves and all

  The liquid mass of water and swimming plains?

  405

  And if he wants us to beware the stroke

  Why is he loth to let us see it coming?

  But if he wants to crush us unawares

  Why does he thunder from the same direction

  And put us on our guard? Why does he first

  Summon the darkness, with its roars and growls?

  410

  And can you possibly believe he shoots

  In many directions simultaneously?

  Or would you dare to say this never happens,

  Never many strikes at the same time?

  In fact this often occurs, and it must be

  That just as rain-showers fall in many places

  415

  So at one time fall many thunderbolts.

  Lastly, why does he wreck the holy shrines of gods

  And his own glorious habitations

  With hostile thunderbolt? Why does he smash

  The noble images of gods, and dishonour

  His own fine statues with a violent wound?

  420

  Why does he mostly strike high ground, why do we see

  The signs of fire most often on the mountain tops?

  From what has been said, it is easy to understand

  Those whirlwinds which the Greeks name from their nature

  Presters, and how they come from above into the sea.

  425

  It sometimes happens that a kind of column

  Is let down from the sky into the sea.

  The waters boil round it, lashed by furious winds,

  And any ships caught in this mighty tumult

  Find themselves storm-tossed, in the greatest danger.

  430

  This happens when sometimes a powerful wind