Diodorus describes the Druids exhorting combatants to peace, and taming them like wild beasts by enchantment.[1043] This suggests interference to prevent the devastating power of the blood-feud or of tribal wars. They also appear to have exercised authority in the election of rulers. Convictolitanis was elected to the magistracy by the priests in Gaul, "according to the custom of the State."[1044] In Ireland, after partaking of the flesh of a white bull, probably a sacrificial animal, a man lay down to sleep, while four Druids chanted over him "to render his witness truthful." He then saw in a vision the person who should be elected king, and what he was doing at the moment.[1045] Possibly the Druids used hypnotic suggestion; the medium was apparently clairvoyant. Dio Chrysostom alleges that kings were ministers of the Druids, and could do nothing without them.[1046] This agrees on the whole with the witness of Irish texts. Druids always accompany the king, and have great influence over him. According to a passage in the _Táin_, "the men of Ulster must not speak before the king, the king must not speak before his Druid," and even Conchobar was silent until the Druid Cathbad had spoken.[1047] This power, resembling that of many other priesthoods, must have helped to balance that of the warrior class, and it is the more credible when we recall the fact that the Druids claimed to have made the universe.[1048] The priest-kingship may have been an old Celtic institution, and this would explain why, once the offices were separated, priests had or claimed so much political power.