Strabo, Geography

As for gods, they honor Helius,¹ Zeus, and Selene,² but especially Selene;³ her temple is near Iberia. The office of priest is held by the man who, after the king, is held in highest honor; he has charge of the sacred land, which is extensive and well-populated, and also of the temple slaves, many of whom are subject to religious frenzy and utter prophecies. And any one of those who, becoming violently possessed, wanders alone in the forests, is by the priest arrested, bound with sacred fetters, and sumptuously maintained during that year, and then led forth to the sacrifice that is performed in honor of the goddess, and, being anointed, is sacrificed along with other victims. The sacrifice is performed as follows: Some person holding a sacred lance, with which it is the custom to sacrifice human victims, comes forward out of the crowd and strikes the victim through the side into the heart, he being not without experience in such a task; and when the victim falls, they draw auguries from his fall⁴ and declare them before the public; and when the body is carried to a certain place, they all trample upon it, thus using it as a means of purification.