On the Nature of the Universe (Oxford World’s Classics)
Page 23
Those many bodies of heat and air, and far from earth
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Uplifted filled the shining vault of heaven.
The plains subsided and the mountains grew,
High mountains, since the rocks could not sink down,
Nor all things everywhere sink equally.
So in this way earth with its solid weight
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Stood, and the mud as it were of all the world
Flowing down together in a heavy mass
Sank to the bottom like the lees of wine.
Then sea, then air, then ether fire-bearer
All were left pure, of liquid atoms made,
Some lighter than others. Liquidest of all,
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And lightest, ether flows above the air,
Nor is its liquid essence e’er disturbed
By whirling winds. It lets all things below
Be tossed by violent tempests, racked by storms;
Itself with motion undisturbed and sure
Bearing its own fires keeps its onward way.
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For that a gentle flow in one direction
Is possible for ether, Pontus shows, a sea
That flows with an unchanging current, keeping
One tide forever moving in its waters.
The causes of the motions of the stars
Let us now sing. First, if the great orb of heaven
Turns round, we must say that air presses on each pole,
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And holds it from outside and shuts it in;
Then, that another air flows above and moves
On the same course as roll the signs of heaven
And shining stars of the everlasting world;
Or else some other air flowing beneath
In the opposite direction drives it from below,
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As we see rivers turning wheels and buckets.
It may be also that the whole of heaven
Remains at rest, and yet the bright stars move;
Whether because swift tides of ether shut in
Seeking escape whirl round in circles, and roll
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Their fires through all the thundering realms of heaven;
Or some air flowing from some place outside
Turns and drives fires; or perhaps of their own accord
They wind where food invites them, fiery bodies
Grazing the starry pastures of the sky.
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Which of these causes operates in this world
It is difficult to say beyond all doubt;
But what can and does happen in the universe
In various worlds created in various ways
That do I teach, and set out several causes
That may apply to the movements of the stars
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Throughout the universe; and one of these
Must certainly within this world of ours
Excite the movements of the constellations;
But to lay down which it is, is not for one
With stumbling footsteps moving slowly forward.
Now earth rests in the centre of the world.
This is because its mass slowly reduces
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And vanishes, and underneath is joined
Another substance, joined when its life began,
Fitted and grafted into the regions of air
In which it lives, and for that very reason
It is no burden and does not depress the air.
A man’s limbs have no weight that he can feel,
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The head’s no burden to the neck, nor body
For all its size weighs heavy on our feet.
But heavy things striking us from outside
Cause injury, though they be very much smaller.
So much it matters what each thing can do.
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In the same way, earth was not suddenly
Imposed on air as something alien,
Or from outside thrust in on alien air,
But from the first beginning of the world
It was conceived and grew together with it,
A fixed part of it, as limbs are of our body.
Besides, when earth by sudden mighty thunder
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Is struck, it shakes all the air that lies above.
This it could never do, were it not bound
To the world’s airy regions and to the sky.
By common roots united and conjoined,
Joined when their lives began, they cling together.
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See also how a most thin essence of spirit
Sustains our body, despite its heavy weight
Because it is so conjoined and united with it.
And what can lift the body in a leap
If not the force of spirit that guides the limbs?
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Now do you see how great the power can be
Of a thin substance joined with heavy body,
As air is joined with earth, and mind with us?
The sun’s heat and its size can hardly be
Much greater or less than is perceived by our senses.
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Though great the distances through which its fires
Throw light, and breathe warm air upon our limbs,
The heat is not lessened by these intervals
Nor is the fire made smaller to our vision;
Therefore since the sun’s heat and light outpoured
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Reach to our senses and shine everywhere,
The shape and size of the sun can so truly be seen
That nothing need be added or taken away.
The moon too, whether it shines with borrowed light
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Illumining the world, or whether it sends
Its own light from its own body, whichever it is,
Its size, as it moves through the heavens, is no larger
Than it appears to our eyes as we see it.
For all things which we see at a great distance
Through large expanse of air have outlines blurred
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Before the bulk is lessened. Therefore the moon,
Since it displays a clear face and firm outline,
Must, as we see it move on high, possess
The same shape and same size as what we see.
Lastly, all the fires of ether which we see—
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Since all the fires that we see here on earth,
So long as their flickering is clear and blaze perceived,
Appear sometimes to change extremely little
In size, however distant they may be—
You may be sure that only by a fraction
Or by a small and trifling difference,
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Can they be smaller or larger than what we see.
And here’s another thing that need not cause surprise.
How does so small a sun so great a light
Send out that floods the seas and lands and sky,
And fills them and bathes them in its glowing heat?
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Perhaps from there one spring of all the world
Wells forth in bounteous flood and pours out light,
Because elements of heat so mass together,
Coming from everywhere through all the world,
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That heat flows out here from one single source.
Do you not see how widely a small spring
Can water the meadows and flood across the fields?
Or it may be that no great heat of sun
Can set the air on fire, if it may chance
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That air is present of a kind that can
Be kindled by a small amount of heat,
As sometimes we see standing corn or stubble
Caught by a single spark blaze everywhere.
Perhaps also the sun with r
osy lamp
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Shining on high possesses hidden fires
Invisible, all round it, with no radiance marked,
And in this way the mighty heat-bearer
Increases the force and impact of its rays.
Nor does a straight and simple path lie open
To tell us how the sun from its summer heights
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Sinks down to Capricorn in winter, then coming back
Turns to its goal again of Cancer’s solstice;
Nor how the moon traverses month by month
The space which the sun takes a full year to travel.
These things, I say, can be given no single cause.
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One of the most likely explanations
Is that put forward by Democritus,
Divine philosopher. In his opinion
The nearer the heavenly bodies are to earth
The less the whirling of the sky can move them;
For its violent and rapid force grows less
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And fades away lower down, and so the sun
Together with the signs that follow it
Is gradually left behind, because its path
Is so much lower than that of the burning stars.
And still more so the moon: its course is lower,
And the further it is from the sky and the nearer to earth
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So much the less it can keep up with the signs.
And as the whirling movement carrying it
Is weaker, since it is lower than the sun,
So much the sooner do the constellations
Catch up with it all round and pass it by.
It seems to travel back more quickly to them
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Because in fact they catch up faster on it.
It is possible also that two currents of air
Blow across the world in opposite directions,
Alternately, each at fixed intervals;
One driving the sun down from its summer signs
To the winter turning point of frost and ice,
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One throwing it back out of the cold and dark
To regions of heat and to the burning stars.
In the same way we must think that the moon
And the stars which turn for great years in great orbits
May be driven by alternate currents of air.
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You see how clouds driven by opposing winds
Move in opposite directions, one above another.
Why should the stars not through the mighty orbits
Of ether be carried by opposing tides?
Night with vast darkness overwhelms the earth
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Either because the sun on its long course
Has reached the farthest limits of the sky,
And faint and weary has breathed out its fires
Worn by the journey and weakened by much air,
Or else it is driven to turn beneath the earth
By the same force that carried it above.
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At a fixed time also Matuta spreads
Her rosy dawn abroad through ether’s shores
And flings wide the light of day; either because
The sun returning from beneath the earth
Comes up and tries to set the sky on fire,
Or because fires and many seeds of heat
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At a fixed time combine and mass together
And make each day a newborn sun to shine.
So it is said from Ida’s mountain peaks
At daybreak in the East strange fires are seen
Scattered along the morning’s rim, which mass
As it were into a ball and form an orb.
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Nor is it anything miraculous
That at so fixed a time these seeds of fire
Combine to make anew the sun’s bright rays.
For we see many things that come to pass
At a fixed time everywhere. At a fixed time
Trees bloom, at a fixed time flowers fall,
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At a fixed time no less does age command
The teeth to fall, brings the soft growth of down
On face of ripening youth and bids the beard
Come down in equal length on manly cheek.
And lightning too and snow, rains, clouds, and winds,
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These mostly come at fixed times of the year.
For since the causes from the first beginning
Were of this nature, and from the world’s origin
Things happened in this way, in sequence then
And order fixed they even now recur.
Days may grow longer and nights melt away
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And daylight lessen as the nights increase
For various reasons. It may be that the sun
Running below and then above the earth
Moves through the ether in unequal curves
Dividing its orbit into unequal parts,
And what from one point it has taken away
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It adds to the other on its journey back,
Until it comes to that great sign in heaven
Where the two knotted circles of the year
Equate the shades of night with light of day.
For in mid-course between the mighty blasts
Of North wind and of South the sky maintains
Its turning points at equal distances,
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Obeying the pattern of the zodiac
Through which the sun creeps on its yearly course
Shining obliquely upon earth and sky.
So they declare who have mapped out all the parts
Of heaven and marked the signs in their due places.
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Or perhaps the air is thicker in certain parts
So that below the earth the trembling gleam
Of fire delays and cannot easily
Pass through and so come forth into its rising.
And therefore the long winter nights drag on
Until the radiant banner of day appears.
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Or again, the truth may lie with those who say
That in alternate seasons of the year
Slower or quicker flow together the fires
That cause the sun to rise in its due place.
Let us now consider the moon. Perhaps it shines
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Because the sun’s rays strike it, day by day
Turning a larger light into our eyes
As it moves further from the sun, until
Rising on high it sees its setting, and then
Right opposite the sun the moon shines full.
Then gradually it must needs hide its light
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Behind it, as it glides nearer to the sun
From the opposite region through the zodiac.
So they make out that say the moon’s like a ball
Moving in an orbit below the sun.
Perhaps also the moon has its own light
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And with it displays its bright shapes as they change.
For there may be some other moving body
That glides along with it, obstructing it
And blocking it in all sorts of ways,
Which cannot be seen because it has no light.
Or it may be that it rotates like a ball
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One half of which is filled with brilliant light
And as it turns displays a changing shape
Until it brings round to our gazing eyes
All of the part that is enriched with fire.
Then gradually as it turns it bears away
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The luminous surface of its rounded globe.
This do the Babylonian Chaldees
Maintain, refuting the astronomers,
And try
ing to prove their art is all in vain.
As if each of these contentions might not be true,
Or there were any reason why you should dare
To embrace one of them rather than another.
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Lastly, why should not a new moon every day
Be created, with fixed phases and fixed shapes,
And every single day the new creation
Perish, and a new one take its place?
That is difficult to explain by reasoning
And prove by words, seeing that many things
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Are created in so fixed and sure an order.
Spring comes, and Venus, and Venus’ harbinger
Winged Cupid runs in front, in Zephyr’s steps,
And mother Flora strews the path before them
With choicest scents and colours everywhere.
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Next follows parching heat and hand in hand
Ceres his dusty friend, and Aquilo
That blows in summertime across the sea;
Next autumn comes and Bacchus’ revel rout;
Then follow other seasons, other winds,
Volturnus thunderer and Auster armed with lightning.
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Last winter brings his snows and freezing frost,
And cold comes after him with chattering teeth.
No marvel then, if at fixed times the moon
Is born and at fixed times again destroyed,
Seeing that in this world so many things
Come into being at so fixed a time.
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The sun’s eclipses and the moon’s retreats
Likewise you must suppose have several causes.
For if the moon can cut the sun’s light off
From earth, with head on high obstructing it,
Blocking its burning rays with its dark orb,
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Why should we not think that some other body
Gliding always without light could do the same?
And why should not the sun at a fixed time
Be able fainting to lay down its fires
And then renew its light, when it has passed
Through regions of air hostile to its flames
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Which can extinguish and destroy its fires?
And if the earth in turn can rob the moon
Of light and keep the sun subdued below
While moon glides monthly through the cone of shadow,
Why should not some other body at the same time
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Be able to travel underneath the moon
Or glide above the sun’s great orb, and so
Block and cut off its rays and light outpoured?
And if the moon shines with its own bright light,
Why should it not in a fixed part of the heavens
Grow faint as it passes through regions hostile to it?
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Well now, since the blue firmament on high
Has been my theme, and I have explained its working,