About the etymology of "Vaticanus" there are several hypotheses: according to Barthold Georg Niebuhr, the toponym perhaps refers to an archaic Etruscan settlement called "Vaticum"; Varro derives the name from a childbirth deity named "Vaticanus" or "Vagitanus", the god of the "vagiti" ("wailings"), since "va" was supposed to be the first syllable pronounced by a child; Aulus Gellius on his part derives the name from "vaticinium", a prophecy elicited by the flight of the birds or from the study of the liver of the victims of sacrifices and inspired by the god who controlled the area: the science of the "Vaticini" , the "aruspicina" or "Etrusca Disciplina", had been introduced in Rome by the Etruscans.