The edition before you represents, in part, a synthesis of centuries of research and deliberation over the text of al-Kafi. More importantly, it represents a very modern effort to update this rich tradition of scholarship by addressing the needs, as we see them, of readers living in the 21st Century. In researching each tradition mentioned in this book, ITI's team has painstakingly combed through the fifteen extant commentaries and annotations on al-Kafi, all of which were written around the 17th Century. Where we found their literary analysis and exegesis to be sound and relevant to the modern reader, we simply narrated and, at most, refined their work. Where we found their work to be wanting, or more often, where they had not addressed issues that are now vital to our understanding, we endeavored to fill the void by writing our own original commentary. We believe this book to be a testament to the continued vibrancy and rigor of Islamic scholarship among the Shi'ah, the followers of Prophet Muhammad and his twelve successors.