Born in 864 near today’s Teheran and died in Baghdad in 941, al-Kulaynī is the author of the most important collection of Shi‘ite hadīths, entitled al-Kāfī (“The Sufficient Book”). The title is an extremely appropriate one, considering the vastness of this collection that forms the first and most ancient among the “four books” of Twelver hadīths. The pivotal role accorded to the imam already emerges from the choice to include in this compilation not only the traditions ascribed to Muhammad, but also those attributed to his successors, thereby significantly expanding the extension of sacred history. Indeed, if, for the Sunnis, revelation closes in 632 with Muhammad’s death, for the Shi‘ites, the imams continued to exercise their teaching authority at least until the physical disappearance of the last of them in 874.
Not a few of these sayings concern indeed the imam’s function, particularly in the chapter entitled The Book of Proof. As in an ascending journey, this starts off with a discussion on the need for an infallible guide inspired by God. This cannot consist – argues the first hadīth proposed – solely in the Qur’an, because Islam’s holy book has been the object of divergent and conflicting interpretations, as evidenced by the existence of numerous schools of theology and law. Thus the Qur’an – the reasoning concludes – needs a “keeper”, in exactly the same way as sense organs need a heart.