El agua raritas de Vitruvio

Abstract

In Book VIII of De Architectura of Vitruvius the substantive raritas indicates the specific quality that allows the water to acquire the characteristics determined by the land through which it flows. This abstract term used for the first time in Cicero, but are very interesting some previous occurrences of the adjective rarus in De rerum natura of Lucretius, which is used by the poet about the structure of material.