27. Some of these things I have seen for myself, others I have found written in Greek books, the authorities for these writings being Theophrastus, Timaeus, Posidonius, Hegesias, Herodotus, Aristides, and Metrodorus. These men with much attention and endless pains showed by their writings that the peculiarities of sites, the properties of waters, and the characteristics of countries are conditioned by the inclination of the heaven. Following their investigations, I have set down in this book what I thought sufficient about different kinds of water, to make it easier, by means of these directions, for people to pick out springs from which they can conduct the water in aqueducts for the use of cities and towns.
28. For it is obvious that nothing in the world is so necessary for use as water, seeing that any living creature can, if deprived of grain or fruit or meat or fish, or any one of them, support life by using other foodstuffs; but without water no animal nor any proper food can be produced, kept in good condition, or prepared.