Meteorology   

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.

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