Meteorology   

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.

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