He was born Muhammad Mohsin ibn Murtadha in 1007 AH in Kashan, Iran, to an eminent scholarly family. After receiving his early education from his father, he moved to Mash'had, where he studied under Sayed Majid Bahraini, Mulla Sadra Shirazi, and Shaikh Bahai.
Mulla Sadra was extremely impressed by his student's skill in matters of logic and philosophy. As such, he gave him the title "Faiz" (benefit). Later on, Mulla Kashani also married the daughter of Mulla Sadra.
Upon completing his education, he returned to his native Kashan in order to serve the people. Because of his excessive interest in philosophy and logic, many ordinary people could not understand his ideas, and several people considered him a heretic. However, the majority realized his academic worth, and he was soon accepted as one of the leading religious authorities.
Mulla Kashani lived in Iran during a period where the followers of the Ahlul Bayt (peace be upon them) enjoyed relative security. During the time of Muhaqqiq al-Karki and Shaikh Bahai, Shia academia had reached new heights, and Shia scholars had been appointed overseers of all legislation. During the time of Mulla Kashani, the Ottoman Empire was starting to launch raids and skirmishes on the Iranian border. Mulla Kashani sensed danger for the future of Shia academia, and he was the first scholar to begin work on a new collection of narrations. His famous 14-volume al-Waafi combines narrations from the first four books of ahadith (i.e. Al-Kafi, Man La Yahduruhul Faqih, Al-Istabsaar, and Tahdeebul Ahkaam) and reorganizes them in a more systematic and orderly manner. He also included explanations and footnotes wherever he deemed appropriate. Today, the book is considered one of the greatest works of narration. In addition to Al-Waafi, he also penned over two hundred other books on jurisprudence, exegesis, philosophy, and logic.
In 1091 AH, Mulla Faiz Kashani passed away at the age of 84. He was buried in his hometown of Kashan. Upon his demise, the reins of the Shia world were taken up by his brilliant student Muhammad Baqir, who is better known today as Allama Majlisi.
EDITOR'S NOTE: These articles are adaptations of lectures delivered by Maulana Sadiq Hasan in Karachi, Pakistan, during the 1980s on the lives of the great scholars of Islam. The Urdu lectures can be accessed at Hussainiat.com. For previous articles in this series, please look under the History section.