Mahadi or Mehdi
Mahadi or Mehdi (Arab. director, sovereign, or pontiff) is the surname, by way of excellence, of the twelfth and last imam (q.v.) of the race of Ali. This Mahadi, who bore the same name with the false prophet, being called Abulcassem Mohammed, was born in the year of the Hegira 255, and, according to Persian tradition, when nine years old, was shut up in a cave or cistern by his mother. and is there kept till he shall appear at the end of the world, and Jesus Christ shall destroy Antichrist, and make of the two laws, the Mussulman and Christian, but one. Some among them believe that this imam was twice hidden; the first time from his birth to the age of 74 years, during which interval he secretly conversed with his disciples without being seen by others, because most of the imams who preceded him had been poisoned by the caliphs, who knew their pretensions, and feared a revolt in their favor. The second retreat of this imam is from the time his death was made known to the time which Providence has appointed for his manifestation. The disciples of this Mahadi give him the title of Motebatthen, the secret or concealed. There is in Chaldaea, in a little province called by the Arabians Ahvaz, a castle named Hesn Mahadi, where all the waters of that country join and form a marsh, which runs into the sea. It is here, according to the Shiites, that Mahadi will make his appearance. See D'Herbelot, Bibl. Orient. s.v.; Broughton, Bibl. Hist. Sac. vol. 2, s.v.; Malcolm, Hist. of Persia, 2:345, note.