On the Nature of the Universe (Oxford World’s Classics) (42 page)

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 rosy 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