This one is interesting--regarding the Byzantine Acclamation, a song performed by priests acknowledging the God-given right of a ruler:


    'The Byzantine Acclamation' – Traditional (fifth century)
    Chosen by Bettany Hughes, research fellow at King's College London, fellow Of the Historical Association, New York Times bestselling author and TV/radio broadcaster

    Bettany says: 'Back in fifth century Byzantium – known as Istanbul today – you had the first combination of church and state. And in order for the crowning ceremony of the emperor and empress to be considered complete, there had to be this sung acclamation from all the Byzantine priests, which effectively said: "God has given you the right to have power over us." It changed history because it was the first attempt by a monarch to claim that they had a divine right to rule. And for the next fifteen hundred years, virtually every other ruler followed suit. If you think about world history, it's been the way it has because it was ruled by monarchs who said they had the right to rule because God gave it to them"