In the year 1165, an enigmatic parchment crossed the threshold of the royal courts of Europe, shattering the medieval worldview and igniting an obsession that would endure for five centuries. Addressed to Manuel I Komnenos, Emperor of the Romans in Constantinople, and subsequently forwarded to Frederick Barbarossa, the Holy Roman Emperor, the letter claimed to be written by the hand of "Prester John, by the power and virtue of God and our Lord Jesus Christ, King of Kings and Lord of Lords."