On the Nature of the Universe (Oxford World’s Classics) Page 17
Should not also and all the more fall off;
Especially since on the outer surface of things
Are many minute bodies which can be cast off
In the same order in which they were before
And keep the shape of the objects, and far more quickly,
Since they are so much less able to be impeded
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Being fewer and placed on the extreme outside.
For many things are thrown off lavishly
Not only from deep within (as we said before)
But from their surfaces, among them colour.
Awnings do this, yellow and red and purple
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Spread over a great theatre, for all to see,
On posts and beams, flapping and billowing;
For then the great assembly massed below,
The scenes on the stage, the grandees in their boxes,
They dye, and make to glow and flow with colour.
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And the more the theatre’s surrounding walls
Enclose it, the more all things with beauty filled
Laugh when the light of day is thus confined.
Therefore, since canvas throws off colour from its surface,
All other things must equally send out
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Thin images from the surface everywhere.
And so there are now fixed outlines of shapes
Of finest texture which fly all around
But individually cannot be seen.
Again, the reason why all smell, smoke, heat,
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And similar things stream out into the air diffused
So widely is that they come up from the depths
And in their tortuous course are split apart,
And there are no straight openings to the paths
Of exit, through which they can push out together.
But on the other hand, when the thin film
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Of surface colour is thrown off, there is nothing
To tear it up, because it lies exposed
And is located on the outer surface.
Lastly, whatever similitudes we see
In mirrors, water, or any shining surface,
Since they possess the same outward appearance
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As those objects, it follows that they must
Consist of images thrown off from them.
There are therefore thin shapes and likenesses
Of things which singly no one can perceive
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Yet being flung back by continual
And instantaneous recoil produce
A vision from the surfaces of mirrors.
Nor is there clearly any other way
In which they could be presented to reproduce
So accurate a likeness of each object.
Now I’ll explain to you how very thin
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Each image is. First since their atoms are
So far below our senses and so much
Smaller than those things which the eyes begin
No longer to see, to confirm this let me explain
In a few words how exceedingly minute
The primal elements of all things are.
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First, there exist some animals so small
That a third part of them is quite invisible.
What do you think one of their guts is like?
The ball of the heart? or the eyes? or limbs and joints?
How small they are! And what too of the atoms
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Of which the mind and spirit are composed?
Do you not see how fine and minute they are?
Consider also things that from their bodies
Emit a pungent small—all-heal, rank wormwood,
Strong southern-wood, astringent centaury
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If you press lightly a leaf of one of them
Between two fingers
[Some lines missing]
Rather you may know that many likenesses
Of things are flying about in many ways
And all beneath the power of our perception.
Now these similitudes cast off from objects
Are not the only ones that fly around.
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Others there are which of their own accord
Come into being and by themselves are formed
In this part of the sky we call the air,
Which formed in many ways are carried aloft
And melting never cease to change their shapes
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And form the outlines of things of many kinds.
We see clouds quickly massing in the sky
That mar the clear face of the firmament
Stroking the air as they move. For often giants
Appear to fly above, casting deep shadows,
Sometimes great mountains and rocks torn off from them
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Seem to confront the sun and pass across it
And then some monster pulling other clouds.
Unceasingly they melt and change their shapes
And take the outlines of forms of every kind.
Now let me tell you how easily and swiftly
These images arise, perpetually
Flowing and falling from things and moving away.
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For there is always something streaming off
From the surface of things which they eject. And this,
When it meets some things, passes through them, like glass
Especially. But when it meets rough stone
Or solid wood at once it is broken up,
And then it cannot reproduce an image.
But when the object opposed is bright and compact
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As a mirror is, none of these things occurs;
For it cannot pass through it, as it does through glass,
And also it cannot be broken up, so much
Safety the smoothness never forgets to give.
That is why the images stream back to us.
However suddenly you place a thing
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In front of a mirror, at once its image appears;
So you may know that from the surface of things
There is a constant and perpetual flow
Of thin shapes and thin tissues everywhere.
Therefore in a short time many images
Come into being, so you may rightly call
The origin of them instantaneous.
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The sun must send out many beams of light
In a short time, to fill the world with it,
So in one moment many images
Are borne in many ways into all parts.
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Whichever way we turn a mirror, something
Makes answer to us of like form and colour.
Consider this now: when the weather has been
Most brilliant, suddenly the sky becomes
Gloomy and ugly so that you might think
That all the dark from Acheron had fled
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And filled the mighty caverns of the sky.
So foul a night of clouds has massed together
And the black face of fear lours from on high;
And the image of these clouds, how small it is,
No man can tell or reasonably describe.
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I now explain how fast these images move
And what velocity as they swim through the air
Is given them, a brief hour for a mighty space,
Where each with varied impulse makes its course.
And this I tell in words both sweet and few.
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Better the swan’s brief song than that cry of cranes
Spread by the south wind through the clouds on high.
First, you may very often see that things
Light and of minute elements move swiftly.
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Because they are made of minute elements
Which are hit, at it were, and cross immediately
The intervening space hit by a blow that follows:
For instantly light follows light, and flash
Is triggered off by flash, like a team of oxen.
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In much the same way therefore the images
Must be able to run through space incalculable
In a moment of time; first, since a very small impulse
From far behind is enough to set them in motion,
Since with so swift a lightness they rush on.
Next, since their texture is so very fine
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That they can easily penetrate anything
And ooze as it were through the intervening air.
Consider this too: certain particles
Which rise from deep down, like the sun’s heat and light,
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Are seen at the very instant of daybreak
Through the whole space of heaven to pour themselves
And fly over land and sea and flood the sky;
What then of those already on the surface
When they are thrown off and nothing checks their flight?
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Faster and further clearly they must go
And cover a distance many times as great
In the same time that it takes the sun
To spread its light abroad across the sky.
This also especially seems to show most truly
The speed at which these images are borne:
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A smooth surface of water is exposed
To a clear sky at night, at once the stars
And constellations of the firmament
Shining serene make answer in the water.
Now do you see how in an instant the image
Falls from the edge of heaven to the edge of earth?
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Wherefore again and yet again I say
How marvellously swift the motion is
Of the bodies which strike our eyes and make us see.
And odours flow perpetually from things,
As cold from rivers, heat from the sun, and spray
From the sea which scours the walls along the shore.
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And always different sounds fly through the air.
Again, a damp taste of salt enters our mouths
When we walk by the sea; and when we watch wormwood
Being mixed with water we sense its bitterness.
So does from all things always something flow
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And everywhere into all parts spreads abroad.
And no delay or rest is given this flow
Since we constantly feel it, and all things always
We can see and smell, and hear the sound of them.
Again, a shape that is handled in the dark
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Is recognized to be the same we see
In the clear light of day. It follows then
That sight and touch derive from a like cause.
If we touch something square and it stimulates
Our senses in the dark, what can it be
That in the light comes to our sight as square,
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If not an image of it?
Images therefore clearly are the cause
Of vision, and without them nothing can be seen.
Now these images I speak of are flying around
Everywhere and sprayed about in all directions;
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But since it is only with our eyes we see them
It follows that only where we turn our sight
There all things strike it with their form and colour.
Also the image enables us to see
How far away things are, and to distinguish
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Distances, for when it is sent off
At once it drives and pushes all the air
That is between the object and our eyes,
And this air all passes through our eyeballs
And brushes the pupils as it were in going through.
This is the reason why we can see how far
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Away things are, and the greater the volume of air
That is driven before it and the longer the stream
That brushes our eyes, the more distant
And far removed the thing is seen to be.
And all this happens extremely rapidly,
You may be sure, so that at the same moment
We see both what a thing is and how far away.
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And here is a thing that need not cause surprise—
That objects can be perceived though the images
That strike our eyes cannot themselves be seen.
For when wind blows slowly on us and bitter cold
Flows round, we do not feel each particle
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Of wind or cold, but rather the whole at once,
And we feel blows falling upon our body, as if
Something were striking it, and giving us the feeling
Of its own body coming from outside.
And when we knock a stone with a toe, we touch
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Just the outer surface of it and the surface colour,
But we do not feel this by our touch, but rather
The hardness of the stone deep down inside.
Now I will tell you why the image is seen
Beyond the mirror; for certainly it seems
To be far withdrawn and lie deeply within.
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We see things in the same way through open doors
When the doorway gives an open view through it
And lets us see many things outside the house.
This vision is caused by a double stream of air.
For first the air this side of the doorposts is seen,
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Then follow the doorposts themselves both right and left,
And then the light outside and the second stream
Of light brushes the eyes, and finally
The objects which are really seen out of doors.
The same thing happens when a mirrored image
Projects itself on to our sight: on its way to our eyes
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It drives and pushes all the air between
Itself and our eyes, and makes us feel this first
Before we see the mirror. But when we have seen
The mirror itself also, at once the image
That travels from us to it and is reflected
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Comes back to our eyes, pushing a stream of air
In front of it, and so this first we sense
Before we see the object in the mirror;
That is why it appears to be so far within it.
Wherefore again and yet again I say
It is by no means right to be surprised
At this appearance of objects reflected
In the surface of a mirror, since they involve
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A double journey with two streams of air.
Now why is it that the right side of our body
Appears in a mirror on the left? This is because
When the approaching image strikes the mirror
It is not turned round intact, but flung straight back
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In reverse, as if someone should throw a mask
Of plaster before it is dry against a pillar
So that it bounces straight back keeping the features
Set on its front, but showing them in reverse.
In this case what was the right eye would become
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The left, and the left eye again the right.
An image may also pass from mirror to mirror
So that five or six reflections are produced.
For things can be out of sight at the back of a house
And yet however far removed they are
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Through twisting passages can all be brought out
By a number of mirrors, and be seen to be inside.
So does the image shine from mirror to mirror.
And when the left is given it comes back right
And then comes back again turned round to the same position.
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Moreover, mirrors that have small sides that are curved
In the same degree as our sides send back images
Right to our right and unreversed. Either
Since the image is carried across from mirror to mirror
And then flies to us having been twice reflected,
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Or since the image is turned round when it approaches
As the curved shape of the mirror turns it towards us.
Sometimes the images march along with us
Keeping step with us and mimicking our gestures.
This is because if you move from a part of a mirror
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At once the images cannot return from that part.
Nature compels all things that strike a mirror
To be reflected back at equal angles.
Now here is another thing: the eyes avoid
Bright objects and refuse to gaze at them.
The sun will blind you if you stare at it.
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This is because its power is very great
And from on high through the pure air the images
Travel with great momentum and strike the eyes
And in so doing disrupt the structure of them.
And any strong brightness often burns the eyes
For the reason that it contains many seeds of fire
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Which cause pain to the eyes by piercing them.
People with jaundice see everything yellow.
This is because many seeds of yellow colour
Stream from their bodies to meet the images of things;
And many such seeds are mingled in their eyes
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And by their contact paint everything with pallor.
Again, we see in the dark things in the light
Because, when the black air of darkness, being nearer,
Has entered our eyes and taken possession of them
There follows immediately a bright clear air
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Which purifies them as it were and scatters
The black shades of the first air; for this bright air
Is made of particles much more minute
And much more mobile and more powerful;
As soon as this has filled the paths of the eyes
And opened them, which previously were beset
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By the black air, at once the images of things
That are in the light follow and make us see them.
But on the contrary, we cannot see
Out of the light things that are in the dark,
And this is why: a grosser air of darkness