Strabo, Geography
H.C. Hamilton, Esq., W. Falconer, M.A., Ed.

Poseidonius says, but I do not know whether truly, that Africa is traversed by few, and those small rivers; yet he speaks of the same rivers, namely those between Lynx and Carthage, which Artemidorus describes as numerous and large. This may be asserted with more truth of the interior of the country, and he himself assigns the reason of it, namely, that in the northern parts of Africa (and the same is said of Ethiopia) there is no rain; in consequence therefore of the drought, pestilence frequently ensues, the lakes are filled with mud only, and locusts appear in clouds.

Poseidonius besides asserts that the eastern parts are moist, because the sun quickly changes its place after rising; and that the western parts are dry, because the sun there turns in his course. Now, drought and moisture depend upon the abundance or scarcity of water, and on the presence or absence of the sun's rays. But Poseidonius means to speak of the effects produced by the sun, which all writers determine by the latitude, north or south; but east and west, as applied to the residence of men, differ in different places, according to the position of each inhabited spot and the change of horizon; so that it cannot be asserted generally of places indefinite in number, that those lying to the east are moist, and those to the west dry: but as applied to the whole earth and such extremes of it as India and Spain, his expressions (east and west) may be just; yet what truth or probability is there in his (attempted) explanation (of the causes of drought and moisture)? for in the continuous and unceasing circuit of the sun, what turn can there be in his course? The rapidity too of his passage through every part is equal. Besides, it is contrary to evidence to say, that the extreme parts of Spain or Mauretania towards the west are drier than all other places, when at the same time they are situated in a temperate climate and have water in great abundance. But if we are to understand the turning of the sun in this way, that there at the extremities of the habitable world he is above the earth, how does that tend to produce drought ? for there, and in other places situated in the same latitude, he leaves them for an equal portion of the night and returns again and warms the earth.