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Meteorology By Aristotle

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Author Topic: Meteorology By Aristotle  (Read 1439 times)
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« Reply #30 on: August 30, 2009, 11:43:50 pm »

We find analogous views about the origin of rivers. It is thought
that the water is raised by the sun and descends in rain and gathers
below the earth and so flows from a great reservoir, all the rivers
from one, or each from a different one. No water at all is generated,
but the volume of the rivers consists of the water that is gathered
into such reservoirs in winter. Hence rivers are always fuller in
winter than in summer, and some are perennial, others not. Rivers
are perennial where the reservoir is large and so enough water has
collected in it to last out and not be used up before the winter rain
returns. Where the reservoirs are smaller there is less water in the
rivers, and they are dried up and their vessel empty before the fresh
rain comes on.

But if any one will picture to himself a reservoir adequate to the
water that is continuously flowing day by day, and consider the amount
of the water, it is obvious that a receptacle that is to contain all
the water that flows in the year would be larger than the earth, or,
at any rate, not much smaller.

Though it is evident that many reservoirs of this kind do exist in
many parts of the earth, yet it is unreasonable for any one to refuse
to admit that air becomes water in the earth for the same reason as
it does above it. If the cold causes the vaporous air to condense
into water above the earth we must suppose the cold in the earth to
produce this same effect, and recognize that there not only exists
in it and flows out of it actually formed water, but that water is
continually forming in it too.
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« Reply #31 on: August 30, 2009, 11:44:09 pm »

Again, even in the case of the water that is not being formed from
day to day but exists as such, we must not suppose as some do that
rivers have their source in definite subterranean lakes. On the contrary,
just as above the earth small drops form and these join others, till
finally the water descends in a body as rain, so too we must suppose
that in the earth the water at first trickles together little by little,
and that the sources of the rivers drip, as it were, out of the earth
and then unite. This is proved by facts. When men construct an aqueduct
they collect the water in pipes and trenches, as if the earth in the
higher ground were sweating the water out. Hence, too, the head-waters
of rivers are found to flow from mountains, and from the greatest
mountains there flow the most numerous and greatest rivers. Again,
most springs are in the neighbourhood of mountains and of high ground,
whereas if we except rivers, water rarely appears in the plains. For
mountains and high ground, suspended over the country like a saturated
sponge, make the water ooze out and trickle together in minute quantities
but in many places. They receive a great deal of water falling as
rain (for it makes no difference whether a spongy receptacle is concave
and turned up or convex and turned down: in either case it will contain
the same volume of matter) and, they also cool the vapour that rises
and condense it back into water.

Hence, as we said, we find that the greatest rivers flow from the
greatest mountains. This can be seen by looking at itineraries: what
is recorded in them consists either of things which the writer has
seen himself or of such as he has compiled after inquiry from those
who have seen them.
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« Reply #32 on: August 30, 2009, 11:44:28 pm »

In Asia we find that the most numerous and greatest rivers flow from
the mountain called Parnassus, admittedly the greatest of all mountains
towards the south-east. When you have crossed it you see the outer
ocean, the further limit of which is unknown to the dwellers in our
world. Besides other rivers there flow from it the Bactrus, the Choaspes,
the Araxes: from the last a branch separates off and flows into lake
Maeotis as the Tanais. From it, too, flows the Indus, the volume of
whose stream is greatest of all rivers. From the Caucasus flows the
Phasis, and very many other great rivers besides. Now the Caucasus
is the greatest of the mountains that lie to the northeast, both as
regards its extent and its height. A proof of its height is the fact
that it can be seen from the so-called 'deeps' and from the entrance
to the lake. Again, the sun shines on its peaks for a third part of
the night before sunrise and again after sunset. Its extent is proved
by the fact that thought contains many inhabitable regions which are
occupied by many nations and in which there are said to be great lakes,
yet they say that all these regions are visible up to the last peak.
From Pyrene (this is a mountain towards the west in Celtice) there
flow the Istrus and the Tartessus. The latter flows outside the pillars,
while the Istrus flows through all Europe into the Euxine. Most of
the remaining rivers flow northwards from the Hercynian mountains,
which are the greatest in height and extent about that region. In
the extreme north, beyond furthest Scythia, are the mountains called
Rhipae. The stories about their size are altogether too fabulous:
however, they say that the most and (after the Istrus) the greatest
rivers flow from them. So, too, in Libya there flow from the Aethiopian
mountains the Aegon and the Nyses; and from the so-called Silver Mountain
the two greatest of named rivers, the river called Chremetes that
flows into the outer ocean, and the main source of the Nile. Of the
rivers in the Greek world, the Achelous flows from Pindus, the Inachus
from the same mountain; the Strymon, the Nestus, and the Hebrus all
three from Scombrus; many rivers, too, flow from Rhodope.

All other rivers would be found to flow in the same way, but we have
mentioned these as examples. Even where rivers flow from marshes,
the marshes in almost every case are found to lie below mountains
or gradually rising ground.
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« Reply #33 on: August 30, 2009, 11:44:44 pm »

It is clear then that we must not suppose rivers to originate from
definite reservoirs: for the whole earth, we might almost say, would
not be sufficient (any more than the region of the clouds would be)
if we were to suppose that they were fed by actually existing water
only and it were not the case that as some water passed out of existence
some more came into existence, but rivers always drew their stream
from an existing store. Secondly, the fact that rivers rise at the
foot of mountains proves that a place transmits the water it contains
by gradual percolation of many drops, little by little, and that this
is how the sources of rivers originate. However, there is nothing
impossible about the existence of such places containing a quantity
of water like lakes: only they cannot be big enough to produce the
supposed effect. To think that they are is just as absurd as if one
were to suppose that rivers drew all their water from the sources
we see (for most rivers do flow from springs). So it is no more reasonable
to suppose those lakes to contain the whole volume of water than these

That there exist such chasms and cavities in the earth we are taught
by the rivers that are swallowed up. They are found in many parts
of the earth: in the Peloponnesus, for instance, there are many such
rivers in Arcadia. The reason is that Arcadia is mountainous and there
are no channels from its valleys to the sea. So these places get full
of water, and this, having no outlet, under the pressure of the water
that is added above, finds a way out for itself underground. In Greece
this kind of thing happens on quite a small scale, but the lake at
the foot of the Caucasus, which the inhabitants of these parts call
a sea, is considerable. Many great rivers fall into it and it has
no visible outlet but issues below the earth off the land of the Coraxi
about the so-called 'deeps of Pontus'. This is a place of unfathomable
depth in the sea: at any rate no one has yet been able to find bottom
there by sounding. At this spot, about three hundred stadia from land,
there comes up sweet water over a large area, not all of it together
but in three places. And in Liguria a river equal in size to the Rhodanus
is swallowed up and appears again elsewhere: the Rhodanus being a
navigable river.
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« Reply #34 on: August 30, 2009, 11:45:02 pm »

Part 14

The same parts of the earth are not always moist or dry, but they
change according as rivers come into existence and dry up. And so
the relation of land to sea changes too and a place does not always
remain land or sea throughout all time, but where there was dry land
there comes to be sea, and where there is now sea, there one day comes
to be dry land. But we must suppose these changes to follow some order
and cycle. The principle and cause of these changes is that the interior
of the earth grows and decays, like the bodies of plants and animals.
Only in the case of these latter the process does not go on by parts,
but each of them necessarily grows or decays as a whole, whereas it
does go on by parts in the case of the earth. Here the causes are
cold and heat, which increase and diminish on account of the sun and
its course. It is owing to them that the parts of the earth come to
have a different character, that some parts remain moist for a certain
time, and then dry up and grow old, while other parts in their turn
are filled with life and moisture. Now when places become drier the
springs necessarily give out, and when this happens the rivers first
decrease in size and then finally become dry; and when rivers change
and disappear in one part and come into existence correspondingly
in another, the sea must needs be affected.

If the sea was once pushed out by rivers and encroached upon the land
anywhere, it necessarily leaves that place dry when it recedes; again,
if the dry land has encroached on the sea at all by a process of silting
set up by the rivers when at their full, the time must come when this
place will be flooded again.
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« Reply #35 on: August 30, 2009, 11:45:20 pm »

But the whole vital process of the earth takes place so gradually
and in periods of time which are so immense compared with the length
of our life, that these changes are not observed, and before their
course can be recorded from beginning to end whole nations perish
and are destroyed. Of such destructions the most utter and sudden
are due to wars; but pestilence or famine cause them too. Famines,
again, are either sudden and severe or else gradual. In the latter
case the disappearance of a nation is not noticed because some leave
the country while others remain; and this goes on until the land is
unable to maintain any inhabitants at all. So a long period of time
is likely to elapse from the first departure to the last, and no one
remembers and the lapse of time destroys all record even before the
last inhabitants have disappeared. In the same way a nation must be
supposed to lose account of the time when it first settled in a land
that was changing from a marshy and watery state and becoming dry.
Here, too, the change is gradual and lasts a long time and men do
not remember who came first, or when, or what the land was like when
they came. This has been the case with Egypt. Here it is obvious that
the land is continually getting drier and that the whole country is
a deposit of the river Nile. But because the neighbouring peoples
settled in the land gradually as the marshes dried, the lapse of time
has hidden the beginning of the process. However, all the mouths of
the Nile, with the single exception of that at Canopus, are obviously
artificial and not natural. And Egypt was nothing more than what is
called Thebes, as Homer, too, shows, modern though he is in relation
to such changes. For Thebes is the place that he mentions; which implies
that Memphis did not yet exist, or at any rate was not as important
as it is now. That this should be so is natural, since the lower land
came to be inhabited later than that which lay higher. For the parts
that lie nearer to the place where the river is depositing the silt
are necessarily marshy for a longer time since the water always lies
most in the newly formed land. But in time this land changes its character,
and in its turn enjoys a period of prosperity. For these places dry
up and come to be in good condition while the places that were formerly
well-tempered some day grow excessively dry and deteriorate. This
happened to the land of Argos and Mycenae in Greece. In the time of
the Trojan wars the Argive land was marshy and could only support
a small population, whereas the land of Mycenae was in good condition
(and for this reason Mycenae was the superior). But now the opposite
is the case, for the reason we have mentioned: the land of Mycenae
has become completely dry and barren, while the Argive land that was
formerly barren owing to the water has now become fruitful. Now the
same process that has taken place in this small district must be supposed
to be going on over whole countries and on a large scale.
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« Reply #36 on: August 30, 2009, 11:45:32 pm »

Men whose outlook is narrow suppose the cause of such events to be
change in the universe, in the sense of a coming to be of the world
as a whole. Hence they say that the sea being dried up and is growing
less, because this is observed to have happened in more places now
than formerly. But this is only partially true. It is true that many
places are now dry, that formerly were covered with water. But the
opposite is true too: for if they look they will find that there are
many places where the sea has invaded the land. But we must not suppose
that the cause of this is that the world is in process of becoming.
For it is absurd to make the universe to be in process because of
small and trifling changes, when the bulk and size of the earth are
surely as nothing in comparison with the whole world. Rather we must
take the cause of all these changes to be that, just as winter occurs
in the seasons of the year, so in determined periods there comes a
great winter of a great year and with it excess of rain. But this
excess does not always occur in the same place. The deluge in the
time of Deucalion, for instance, took place chiefly in the Greek world
and in it especially about ancient Hellas, the country about Dodona
and the Achelous, a river which has often changed its course. Here
the Selli dwelt and those who were formerly called Graeci and now
Hellenes. When, therefore, such an excess of rain occurs we must suppose
that it suffices for a long time. We have seen that some say that
the size of the subterranean cavities is what makes some rivers perennial
and others not, whereas we maintain that the size of the mountains
is the cause, and their density and coldness; for great, dense, and
cold mountains catch and keep and create most water: whereas if the
mountains that overhang the sources of rivers are small or porous
and stony and clayey, these rivers run dry earlier. We must recognize
the same kind of thing in this case too. Where such abundance of rain
falls in the great winter it tends to make the moisture of those places
almost everlasting. But as time goes on places of the latter type
dry up more, while those of the former, moist type, do so less: until
at last the beginning of the same cycle returns.
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« Reply #37 on: August 30, 2009, 11:45:45 pm »

Since there is necessarily some change in the whole world, but not
in the way of coming into existence or perishing (for the universe
is permanent), it must be, as we say, that the same places are not
for ever moist through the presence of sea and rivers, nor for ever
dry. And the facts prove this. The whole land of the Egyptians, whom
we take to be the most ancient of men, has evidently gradually come
into existence and been produced by the river. This is clear from
an observation of the country, and the facts about the Red Sea suffice
to prove it too. One of their kings tried to make a canal to it (for
it would have been of no little advantage to them for the whole region
to have become navigable; Sesostris is said to have been the first
of the ancient kings to try), but he found that the sea was higher
than the land. So he first, and Darius afterwards, stopped making
the canal, lest the sea should mix with the river water and spoil
it. So it is clear that all this part was once unbroken sea. For the
same reason Libya-the country of Ammon-is, strangely enough, lower
and hollower than the land to the seaward of it. For it is clear that
a barrier of silt was formed and after it lakes and dry land, but
in course of time the water that was left behind in the lakes dried
up and is now all gone. Again the silting up of the lake Maeotis by
the rivers has advanced so much that the limit to the size of the
ships which can now sail into it to trade is much lower than it was
sixty years ago. Hence it is easy to infer that it, too, like most
lakes, was originally produced by the rivers and that it must end
by drying up entirely.

Again, this process of silting up causes a continuous current through
the Bosporus; and in this case we can directly observe the nature
of the process. Whenever the current from the Asiatic shore threw
up a sandbank, there first formed a small lake behind it. Later it
dried up and a second sandbank formed in front of the first and a
second lake. This process went on uniformly and without interruption.
Now when this has been repeated often enough, in the course of time
the strait must become like a river, and in the end the river itself
must dry up.
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« Reply #38 on: August 30, 2009, 11:46:09 pm »

So it is clear, since there will be no end to time and the world is
eternal, that neither the Tanais nor the Nile has always been flowing,
but that the region whence they flow was once dry: for their effect
may be fulfilled, but time cannot. And this will be equally true of
all other rivers. But if rivers come into existence and perish and
the same parts of the earth were not always moist, the sea must needs
change correspondingly. And if the sea is always advancing in one
place and receding in another it is clear that the same parts of the
whole earth are not always either sea or land, but that all this changes
in course of time.

So we have explained that the same parts of the earth are not always
land or sea and why that is so: and also why some rivers are perennial
and others not.



Part 1

Let us explain the nature of the sea and the reason why such a large
mass of water is salt and the way in which it originally came to be.

The old writers who invented theogonies say that the sea has springs,
for they want earth and sea to have foundations and roots of their
own. Presumably they thought that this view was grander and more impressive
as implying that our earth was an important part of the universe.
For they believed that the whole world had been built up round our
earth and for its sake, and that the earth was the most important
and primary part of it. Others, wiser in human knowledge, give an
account of its origin. At first, they say, the earth was surrounded
by moisture. Then the sun began to dry it up, part of it evaporated
and is the cause of winds and the turnings back of the sun and the
moon, while the remainder forms the sea. So the sea is being dried
up and is growing less, and will end by being some day entirely dried
up. Others say that the sea is a kind of sweat exuded by the earth
when the sun heats it, and that this explains its saltness: for all
sweat is salt. Others say that the saltness is due to the earth. Just
as water strained through ashes becomes salt, so the sea owes its
saltness to the admixture of earth with similar properties.
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« Reply #39 on: August 30, 2009, 11:46:21 pm »

We must now consider the facts which prove that the sea cannot possibly
have springs. The waters we find on the earth either flow or are stationary.
All flowing water has springs. (By a spring, as we have explained
above, we must not understand a source from which waters are ladled
as it were from a vessel, but a first point at which the water which
is continually forming and percolating gathers.) Stationary water
is either that which has collected and has been left standing, marshy
pools, for instance, and lakes, which differ merely in size, or else
it comes from springs. In this case it is always artificial, I mean
as in the case of wells, otherwise the spring would have to be above
the outlet. Hence the water from fountains and rivers flows of itself,
whereas wells need to be worked artificially. All the waters that
exist belong to one or other of these classes.

On the basis of this division we can sec that the sea cannot have
springs. For it falls under neither of the two classes; it does not
flow and it is not artificial; whereas all water from springs must
belong to one or other of them. Natural standing water from springs
is never found on such a large scale.

Again, there are several seas that have no communication with one
another at all. The Red Sea, for instance, communicates but slightly
with the ocean outside the straits, and the Hyrcanian and Caspian
seas are distinct from this ocean and people dwell all round them.
Hence, if these seas had had any springs anywhere they must have been

It is true that in straits, where the land on either side contracts
an open sea into a small space, the sea appears to flow. But this
is because it is swinging to and fro. In the open sea this motion
is not observed, but where the land narrows and contracts the sea
the motion that was imperceptible in the open necessarily strikes
the attention.
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« Reply #40 on: August 30, 2009, 11:46:39 pm »

The whole of the Mediterranean does actually flow. The direction of
this flow is determined by the depth of the basins and by the number
of rivers. Maeotis flows into Pontus and Pontus into the Aegean. After
that the flow of the remaining seas is not so easy to observe. The
current of Maeotis and Pontus is due to the number of rivers (more
rivers flow into the Euxine and Maeotis than into the whole Mediterranean
with its much larger basin), and to their own shallowness. For we
find the sea getting deeper and deeper. Pontus is deeper than Maeotis,
the Aegean than Pontus, the Sicilian sea than the Aegean; the Sardinian
and Tyrrhenic being the deepest of all. (Outside the pillars of Heracles
the sea is shallow owing to the mud, but calm, for it lies in a hollow.)
We see, then, that just as single rivers flow from mountains, so it
is with the earth as a whole: the greatest volume of water flows from
the higher regions in the north. Their alluvium makes the northern
seas shallow, while the outer seas are deeper. Some further evidence
of the height of the northern regions of the earth is afforded by
the view of many of the ancient meteorologists. They believed that
the sun did not pass below the earth, but round its northern part,
and that it was the height of this which obscured the sun and caused

So much to prove that there cannot be sources of the sea and to explain
its observed flow.

Part 2

We must now discuss the origin of the sea, if it has an origin, and
the cause of its salt and bitter taste.

What made earlier writers consider the sea to be the original and
main body of water is this. It seems reasonable to suppose that to
be the case on the analogy of the other elements. Each of them has
a main bulk which by reason of its mass is the origin of that element,
and any parts which change and mix with the other elements come from
it. Thus the main body of fire is in the upper region; that of air
occupies the place next inside the region of fire; while the mass
of the earth is that round which the rest of the elements are seen
to lie. So we must clearly look for something analogous in the case
of water. But here we can find no such single mass, as in the case
of the other elements, except the sea. River water is not a unity,
nor is it stable, but is seen to be in a continuous process of becoming
from day to day. It was this difficulty which made people regard the
sea as the origin and source of moisture and of all water. And so
we find it maintained that rivers not only flow into the sea but originate
from it, the salt water becoming sweet by filtration.

But this view involves another difficulty. If this body of water is
the origin and source of all water, why is it salt and not sweet?
The reason for this, besides answering this question, will ensure
our having a right first conception of the nature of the sea.
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« Reply #41 on: August 30, 2009, 11:46:52 pm »

The earth is surrounded by water, just as that is by the sphere of
air, and that again by the sphere called that of fire (which is the
outermost both on the common view and on ours). Now the sun, moving
as it does, sets up processes of change and becoming and decay, and
by its agency the finest and sweetest water is every day carried up
and is dissolved into vapour and rises to the upper region, where
it is condensed again by the cold and so returns to the earth. This,
as we have said before, is the regular course of nature.

Hence all my predecessors who supposed that the sun was nourished
by moisture are absurdly mistaken. Some go on to say that the solstices
are due to this, the reason being that the same places cannot always
supply the sun with nourishment and that without it he must perish.
For the fire we are familiar with lives as long as it is fed, and
the only food for fire is moisture. As if the moisture that is raised
could reach the sun! or this ascent were really like that performed
by flame as it comes into being, and to which they supposed the case
of the sun to be analogous! Really there is no similarity. A flame
is a process of becoming, involving a constant interchange of moist
and dry. It cannot be said to be nourished since it scarcely persists
as one and the same for a moment. This cannot be true of the sun;
for if it were nourished like that, as they say it is, we should obviously
not only have a new sun every day, as Heraclitus says, but a new sun
every moment. Again, when the sun causes the moisture to rise, this
is like fire heating water. So, as the fire is not fed by the water
above it, it is absurd to suppose that the sun feeds on that moisture,
even if its heat made all the water in the world evaporate. Again,
it is absurd, considering the number and size of the stars, that these
thinkers should consider the sun only and overlook the question how
the rest of the heavenly bodies subsist. Again, they are met by the
same difficulty as those who say that at first the earth itself was
moist and the world round the earth was warmed by the sun, and so
air was generated and the whole firmament grew, and the air caused
winds and solstices. The objection is that we always plainly see the
water that has been carried up coming down again. Even if the same
amount does not come back in a year or in a given country, yet in
a certain period all that has been carried up is returned. This implies
that the celestial bodies do not feed on it, and that we cannot distinguish
between some air which preserves its character once it is generated
and some other which is generated but becomes water again and so perishes;
on the contrary, all the moisture alike is dissolved and all of it
condensed back into water.
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« Reply #42 on: August 30, 2009, 11:47:06 pm »

The drinkable, sweet water, then, is light and is all of it drawn
up: the salt water is heavy and remains behind, but not in its natural
place. For this is a question which has been sufficiently discussed
(I mean about the natural place that water, like the other elements,
must in reason have), and the answer is this. The place which we see
the sea filling is not its natural place but that of water. It seems
to belong to the sea because the weight of the salt water makes it
remain there, while the sweet, drinkable water which is light is carried
up. The same thing happens in animal bodies. Here, too, the food when
it enters the body is sweet, yet the residuum and dregs of liquid
food are found to be bitter and salt. This is because the sweet and
drinkable part of it has been drawn away by the natural animal heat
and has passed into the flesh and the other parts of the body according
to their several natures. Now just as here it would be wrong for any
one to refuse to call the belly the place of liquid food because that
disappears from it soon, and to call it the place of the residuum
because this is seen to remain, so in the case of our present subject.
This place, we say, is the place of water. Hence all rivers and all
the water that is generated flow into it: for water flows into the
deepest place, and the deepest part of the earth is filled by the
sea. Only all the light and sweet part of it is quickly carried off
by the sun, while herest remains for the reason we have explained.
It is quite natural that some people should have been puzzled by the
old question why such a mass of water leaves no trace anywhere (for
the sea does not increase though innumerable and vast rivers are flowing
into it every day.) But if one considers the matter the solution is
easy. The same amount of water does not take as long to dry up when
it is spread out as when it is gathered in a body, and indeed the
difference is so great that in the one case it might persist the whole
day long while in the other it might all disappear in a moment-as
for instance if one were to spread out a cup of water over a large
table. This is the case with the rivers: all the time they are flowing
their water forms a compact mass, but when it arrives at a vast wide
place it quickly and imperceptibly evaporates.
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« Reply #43 on: August 30, 2009, 11:47:20 pm »

But the theory of the Phaedo about rivers and the sea is impossible.
There it is said that the earth is pierced by intercommunicating channels
and that the original head and source of all waters is what is called
Tartarus-a mass of water about the centre, from which all waters,
flowing and standing, are derived. This primary and original water
is always surging to and fro, and so it causes the rivers to flow
on this side of the earth's centre and on that; for it has no fixed
seat but is always oscillating about the centre. Its motion up and
down is what fills rivers. Many of these form lakes in various places
(our sea is an instance of one of these), but all of them come round
again in a circle to the original source of their flow, many at the
same point, but some at a point opposite to that from which they issued;
for instance, if they started from the other side of the earth's centre,
they might return from this side of it. They descend only as far as
the centre, for after that all motion is upwards. Water gets its tastes
and colours from the kind of earth the rivers happened to flow through.

But on this theory rivers do not always flow in the same sense. For
since they flow to the centre from which they issue forth they will
not be flowing down any more than up, but in whatever direction the
surging of Tartarus inclines to. But at this rate we shall get the
proverbial rivers flowing upwards, which is impossible. Again, where
is the water that is generated and what goes up again as vapour to
come from? For this must all of it simply be ignored, since the quantity
of water is always the same and all the water that flows out from
the original source flows back to it again. This itself is not true,
since all rivers are seen to end in the sea except where one flows
into another. Not one of them ends in the earth, but even when one
is swallowed up it comes to the surface again. And those rivers are
large which flow for a long distance through a lowying country, for
by their situation and length they cut off the course of many others
and swallow them up. This is why the Istrus and the Nile are the greatest
of the rivers which flow into our sea. Indeed, so many rivers fall
into them that there is disagreement as to the sources of them both.
All of which is plainly impossible on the theory, and the more so
as it derives the sea from Tartarus.

Enough has been said to prove that this is the natural place of water
and not of the sea, and to explain why sweet water is only found in
rivers, while salt water is stationary, and to show that the sea is
the end rather than the source of water, analogous to the residual
matter of all food, and especially liquid food, in animal bodies.
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« Reply #44 on: August 30, 2009, 11:47:36 pm »

Part 3

We must now explain why the sea is salt, and ask whether it eternally
exists as identically the same body, or whether it did not exist at
all once and some day will exist no longer, but will dry up as some
people think.

Every one admits this, that if the whole world originated the sea
did too; for they make them come into being at the same time. It follows
that if the universe is eternal the same must be true of the sea.
Any one who thinks like Democritus that the sea is diminishing and
will disappear in the end reminds us of Aesop's tales. His story was
that Charybdis had twice sucked in the sea: the first time she made
the mountains visible; the second time the islands; and when she sucks
it in for the last time she will dry it up entirely. Such a tale is
appropriate enough to Aesop in a rage with the ferryman, but not to
serious inquirers. Whatever made the sea remain at first, whether
it was its weight, as some even of those who hold these views say
(for it is easy to see the cause here), or some other reason-clearly
the same thing must make it persist for ever. They must either deny
that the water raised by the sun will return at all, or, if it does,
they must admit that the sea persists for ever or as long as this
process goes on, and again, that for the same period of time that
sweet water must have been carried up beforehand. So the sea will
never dry up: for before that can happen the water that has gone up
beforehand will return to it: for if you say that this happens once
you must admit its recurrence. If you stop the sun's course there
is no drying agency. If you let it go on it will draw up the sweet
water as we have said whenever it approaches, and let it descend again
when it recedes. This notion about the sea is derived from the fact
that many places are found to be drier now than they once were. Why
this is so we have explained. The phenomenon is due to temporary excess
of rain and not to any process of becoming in which the universe or
its parts are involved. Some day the opposite will take place and
after that the earth will grow dry once again. We must recognize that
this process always goes on thus in a cycle, for that is more satisfactory
than to suppose a change in the whole world in order to explain these
facts. But we have dwelt longer on this point than it deserves.
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