Natural Questions Chapter 3

Ut stet aqua aut fluat, loci positio eficit: in deuexo fluit, in plano et defosso continetur et stagnat. Aliquando in aduersum spiritu impellitur: tunc cogitur, non fluit. Colligitur ex imbribus, ex suo fonte natiua est. Nihil tamen prohibet eodem loco aquam colligi et nasci; quod in Fucino uidemus, in quem montes circumiecti, quicquid fudit pluuia, deriuant, sed et magnae in ipso latentesque uenae sunt: itaque etiam cum hiberni defluxere torrentes, faciem suam seruat.

Ce qui rend l’eau stagnante ou courante, c’est la disposition des lieux : elle coule sur les plans inclinés ; en plaine, elle s’arrête immobile ; quelquefois le vent la pousse devant lui ; il y a alors contrainte plutôt qu’écoulement. Les amas d’eau proviennent des pluies ; les cours naturels naissent des sources. Rien n’empêche cependant que l’eau soit recueillie et naisse sur le même point ; témoin le lac Fucin, où les montagnes circonvoisines déversent leurs eaux pluviales . Mais il recèle aussi dans son bassin des sources abondantes ; tellement que quand les torrents de l’hiver s’y jettent, son aspect ne change pas.

The lie of the ground makes water either stand or run; on a slope it flows down, a plain keeps it in, causing it to stagnate. Sometimes under pressure of air it is forced uphill; it is then driven, it does not flow. Surface water comes from rain; spring water from a natural fountain. There is, however, nothing to prevent surface and spring water in the same spot. This we see in Lake Fucinus, into which the streams drain all the rainfall of the surrounding mountains, while there are also large springs concealed under the surface of the lake itself. So, even when the torrents discharge into it in winter, it preserves its appearance unaltered.