The Position and Shape of the Earth

What is the position and shape of the earth? Is it at rest or in motion?

1. Those who believe in a finite whole heaven say that the Earth lies at the centre.

But the Italian philosophers known as Pythagoreans take the contrary view.

They say that at the centre is fire.*

• the earth is one of the stars, creating night and day by its circular motion about the centre.

They further construct another earth in opposition to ours which they call the counterearth.

But many others agree that it is wrong to give the earth the central position.

They believe that the most precious thing should be in the center.

Fire, they say, is more precious than earth and so fire is in the center.

The Pythagoreans hold that the most important part of the world is the centre.

• This center should be most strictly guarded.
• They call this the ‘Guardhouse of Zeus’

They use the word ‘centre’ unequivocally:

• The centre of the mathematical shape is the same as a natural center.

But it is better to conceive of the case of the whole heaven as analogous to that of animals, in which the centre of the animal and that of the body are different.

This is why they have no need to be so disturbed about the world, or to call in a guard for its centre: rather let them look for the centre in the other sense and tell us what it is like and where nature has set it.

That centre will be something primary and precious; but to the mere position we should give the last place rather than the first.

For the middle is what is defined, and what defines it is the limit, and that which contains or limits is more precious than that which is limited, see ing that the latter is the matter and the former the essence of the system.

2. There is also no agreement whether the earth is moving or not.

Those who deny that the earth lies at the centre think that it, and the counter-earth, revolve around the centre.

Some of them even consider it possible that there are several bodies so moving, which are invisible to us owing to the interposition of the earth.

They say:

• this explains why the eclipses of the moon are more frequent than eclipses of the sun.
  • For in addition to the earth each of these moving bodies can obstruct it.
• the earth is far from the center by a full hemisphere

In Timaeus, the earth lies at the centre but is ‘rolled’ and thus in motion around the axis of the whole heaven

The Shape of the Earth

3. Some think the Earth is spherical, others that it is flat and drum-shaped.

For evidence they bring the fact that, as the sun rises and sets, the part concealed by the earth shows a straight and not a curved edge.

If the earth were spherical, then the line of section would have to be circular.

But they disregard:

• the great distance of the sun from the earth
• the great size of the circumference

When seen from afar on these apparently small circles, these appear straight.

Such an appearance should not tomake them doubt the circular shape of the earth.

They also say that because it is at rest, the earth must necessarily have this shape.

For there are many different ways in which the movement or rest of the earth has been conceived.

If you toss dust in the air, it should move if the earth were in motion. But it does not.

Yet here is this great weight of earth, and it is at rest.

If you remove the Earth, the dust will continue its downward movement.

Some like Xenophanes of Colophon have asserted that the earth below us is infinite — it has ‘pushed its roots to infinity. This is to save the trouble of seeking for the cause.

Hence the sharp rebuke of Empedocles, in the words ‘if the deeps of the earth are endless and endless the ample ether-such is the vain tale told by many a tongue, poured from the mouths of those who have seen but little of the whole. Others say the earth rests upon water.

This is the oldest theory that has been preserved, and is attributed to Thales of Miletus.

It says that the earth stays still because it floated like wood.

As if the same account had not to be given of the water which carries the earth as of the earth itself!

It is not the nature of water, any more than of earth, to stay in mid-air: it must have something to rest upon.

Again, as air is lighter than water, so is water than earth: how then can they think that the naturally lighter substance lies below the heavier?

If the earth as a whole can float on water, that must obviously be the case with any part of it.

But observation shows that this is not the case.

Any piece of earth goes to the bottom, the quicker the larger it is.

These thinkers seem to push their inquiries some way into the problem, but not so far as they might.