Meteorology   

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.

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 springs.

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