The twelfth Imam’s name is Muhammad al-Mahdi:
“the one who guides divinely.” He is often referred to by
a host of other names, including Al-Qaim, “He Who
Rises Up”; Sahib as-Zaman, “Lord of the Ages”; and Al-
Muntazar, the “Awaited One.” Mostly, though, he is
known simply as the Mahdi.
It is said that he was the sole child of a clandestine
marriage between the eleventh Imam and a captive
granddaughter of the Byzantine emperor, and that his
birth was kept secret lest Abbasid poisons ɹnd him too.
But on the death of his father in the year 872, when he
was only ɹve years old, a far more radical means of
protection was needed, so it is the core tenet of
mainstream Shia belief that in that year the Mahdi
evaded the fate of his predecessors by descending into a
cave beneath Samarra.
He did not die in that cave, but entered a state of
ghrayba, “occultation,” a strictly correct translation that
is also perfect in the spiritual sense, since it comes from
astronomy, where it refers to one planetary body’s
passing in front of another, hiding it from view. An
eclipse of the sun or the moon is a matter of occultation,
the source of light hidden and yet the light itself
radiating out around the edges. But more plainly
speaking, ghrayba means simply “concealment,” which
is why the Mahdi is often called the Hidden Imam.
This concealment is not permanent. It is a temporary