For the sake of concision, and to avoid repeating what has already been explained, we will limit ourselves to recalling that in Shī'ism, the question of the Caliphate is eminently transcendental. As such, 'Alī's right to succession cannot, in any way, be subjected to human scrutiny. For Shī'ites, the supreme spiritual status of 'Alī is peerless and cannot be compared to the rank held by other Islāmic leaders. He belongs to a unique and superior spiritual category which was conferred on him by the grace of God.
By bestowing the wilāyah of the Prophet on Alī, God perfected Islām and brought the prophetic mission to a close. The fundamental doctrine of wilāyah is based on the concept of the ta'ālīm of the Imāms. What continues in Islām under the name of wilāyah is, de facto et de iure [by fact and by right], a form of esoteric guidance [al-hidāyah al-bātiniyyah] from which humanity cannot stray without perishing.1
The wilāyah is the guaranteed living embodiment of the spiritual authority of the Prophet which, by the temporal succession of the Twelve Imāms, continues throughout human history until the end of times. Understandably, it is impossible to separate the historical development of Shī'ite Islām from the meta-historical antecedents of wilāyah. 'Alī's Islām cannot be separated from the metaphysical truths which are its telos, its fundamental and final cause. In closing, it is inconceivable to claim that we have dealt with the issue of Imāmate and wilāyah in all of its depth.
We have limited ourselves to addressing the issue of its origins and leaving the topic open to further research. As a result, this study on the origins of Shī'ism must remain incomplete for the time being. In order for it to be complete, it would have been necessary to compile some of the traditions that attest to the extraordinary importance of the secret spiritual life of Shī'ism and the Shī'ite ethos of the Hidden Imām, the seal of the Muhammadan wilāyah, for, as the Prophet has stated, without the continuous living presence of the Imām, neither human beings nor the world can subsist.2