A series of letters discussing and debating basic Shīʿa and Sunnī beliefs between the late Shīʿa scholar Sayyid Sharaf al-Dīn, and the late Sunnī scholar and head of Al-Azhar university of that time, Shaykh Salīm al-Bishrī. The written form of the debates in book, has the advantage that the two parties had the opportunity to provide the best possible replies they could give. The book is written without any disrespect and under mutual fairness. This is one of the most important books that provides a well-argued account of Shīʿa beliefs, drawing upon reliable sources with a persuasive tone.