A messianic title meaning 'The One Who Will Lead Us to Paradise', a concept recurring among peoples suffering oppression. Among the Fremen, the Mahdi expectancy combined spiritual hope with military aspiration, fuelled by Harkonnen brutality and the ecological dream of Liet-Kynes. When Paul Muad'Dib made himself known as Mahdi, he used the existing expectation to establish spiritual and military leadership over the Fremen while preserving the autonomy of individual sietches and the authority of their Naibs.