In this work, Syrian Catholic priest Isaac Armalet (d. 1954) investigates the subject of papal authority biblically and historically with respect to the Syrian Catholic Church. The book is divided into four parts: 1. The Unity of the Church, 2. The Unity of Authority, 3. The Unity of Petrine Authority in the Era of the Apostles, and 4. The Unity of Papal Succession in Petrine Authority. The first part lays the groundwork for the concept of papal authority, and the second and third parts investigate several biblical passages pertinent to Peter’s position as head of the disciples. The fourth part deals with ecumenical considerations, liturgy and church calendar, as well as specific subsections on Ephrem, Isaac of Antioch, Severus of Antioch, Barhebraeus, Dayr al-Za‘faran, the church in Aleppo, and Syrian Orthodox Patriarch Ignatius Ni‘matullah.