Because human beings do not have the capacity to attain knowledge of God on their own, the Imam becomes a continuous necessity for all societies and in every era. So in addition to the "fixed" number of Imams who succeeded Muhammad's earthly authority, there must also exist an "ever-present" or "pre-existent" Imam who, as the eternal guardian of the Revelation, functions as "the Proof of God on Earth." Thus, the first Imam was neither Muhammad nor Ali but Adam.
( Reza Aslan )
[ No god but God: The Origins, ]
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