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.
To return to the saltness of the sea: those who create the sea
once for all, or indeed generate it at all, cannot account for its
saltness. It makes no difference whether the sea is the residue of all
the moisture that is about the earth and has been drawn up by the sun,
or whether all the flavour existing in the whole mass of sweet water
is due to the admixture of a certain kind of earth. Since the total
volume of the sea is the same once the water that evaporated has
returned, it follows that it must either have been salt at first
too, or, if not at first, then not now either. If it was salt from the
very beginning, then we want to know why that was so; and why, if salt
water was drawn up then, that is not the case now.
Again, if it is maintained that an admixture of earth makes the
sea salt (for they say that earth has many flavours and is washed down
by the rivers and so makes the sea salt by its admixture), it is
strange that rivers should not be salt too. How can the admixture of
this earth have such a striking effect in a great quantity of water
and not in each river singly? For the sea, differing in nothing from
rivers but in being salt, is evidently simply the totality of river
water, and the rivers are the vehicle in which that earth is carried
to their common destination.
It is equally absurd to suppose that anything has been explained
by calling the sea 'the sweat of the earth', like Empedicles.
Metaphors are poetical and so that expression of his may satisfy the
requirements of a poem, but as a scientific theory it is