One of the most celebrated religious authorities and a foundational figure of Shiʿi Islam, Muḥammad ibn Yaʿqūb al-Kulaynī (d. ca. 940 CE) set out an extraordinarily wide-ranging and coherent set of doctrinal and legal traditions derived from the Shiʿi Imams, thus playing a leading role in the unification and, consequently, the consolidation of the Imami faith. His Book of the Proof (Kitāb al-Ḥujja), part of the Sufficient Book (Kitāb al-Kāfī), is considered the first among the four most important works on Shiʿi hadith, and its significance for the formation and development of Shiʿi beliefs and doctrines cannot be overestimated.

The present volume is an English translation of the award-winning French translation and commentary by Mohammad Ali Amir-Moezzi on the Book of the Proof. Amir-Moezzi’s approach to the study of the early Shiʿi traditions in this work is characterised by a keen interest in the esoteric, mystical aspects. By elaborating on the nature of the ‘Proof’, which in Shiʿi terminology identifies the central figure, i.e. the guide (Imam) of mystical spirituality, Amir-Moezzi’s study portrays Shiʿi Islam, not merely as the politico-religious ideology of its ‘clergy’, but above all as a multifaceted and inspirational religion.