On the first say when Muad’Dib rode through the streets of Arrakeen with his family, some of the people along the way recalled the legends and the prophecy and they ventured to shout: “Mahdi!” But their shout was more a question than a statement, for as yet they could only hope he was the one foretold as the Lisan al-Gaib, the Voice from the Outer World. Their attention was focused, too, on the mother, because they had heard she was a Bene Gesserit and it was obvious to them that she was like the other Lisan al-Gaib.

-From “Manual of Muad’Dib” by the Princess Irulan