“Hamiduddin Kirmani was born most probably in 352/933. His family hailed from Kirman as his name indicates, but it is not known where he was born. He first studied the esoteric science under Abu Yaqub al-Sijjistani (d. 360/971), and then went to Cairo for further studies.
He played some key roles in political and doctrinal matters. He lived at the time when conflict between the Fatimid and the Abbasid was rather serious. The title of his book, al-Majalis al-Baghdadiyyah wal Basariyyah suggests that gatherings were held where he taught Ismaili doctrines in Baghdad and Basra. He exercised some important mission works in Baghdad and Basra. In 380/990, his mission was able to gain support of the Uqayti princes of Mosul, known as al-Musayyib. He passed most part of his life as a hujjat al-Iraqin in Iraq and was expressly summoned in Cairo on 400/1009 for refuting the Druzes who propagated the divinity of al-Hakim. His fame does not stem only from being a pioneer da’i, but also from being one of the most distinguished philosophers and writers. He returned back to Iraq, where he completed his principal work, Rahat al-Aqal in 411/1020. The exact date of his death is unknown; but it appears that he was still living in 412/1021 and died soon. He also compiled some 39 important books on different subjects. In his al-Aqwal al-Dhahabiyyah (ed. Salah al-Sawy, Tehran, 1977, p. 1), Seyyed Hossein Nasr writes in its introduction that, “Hamid al-Din was a very prolific writer who must be considered as one of the most outstanding philosophers not only of Ismailism but also of Islam in general, a figure whose works have been singularly neglected until now by the world of scholarship in general and even by specialists of Islamic philosophy and theology.” In sum, Kirmani has been called “the Shaikh of Ismaili philosophers”, vide the introduction of Kamil Hussain and Mustapha Hilmi to Rahat al-Aqal (Cairo, 1952, p. 17).