Maronite polymath, Custodian of the Vatican Library, and titular bp. of Tyre. Born at Hasrun, he was educated from an early age at the Maronite College in Rome. From 1715–7 he travelled in the Middle East, collecting mss., including many from Dayr al-Suryān in the Nitrian Desert. In 1739 he was appointed First Custodian of the Vatican Library, a post he held until his death. It was on the basis of the Syriac mss., in large part from Dayr al-Suryān, that he compiled his monumental Bibliotheca Orientalis Clementino-Vaticana, in four volumes (1719–28; repr. 1975, with ‘Postface’ by J.-M. Sauget; and 2002). This was effectively the first European history of Syriac literature, and it remains an important resource even today, thanks to the many extensive excerpts of Syriac texts. The volumes are arranged as follows: I, Orthodox (i.e., Chalcedonian) authors; II, Syrian Orthodox writers; III.1, literature of the Church of the East, and III.2, history of the Church of the East. (III.1, 3–362 contains an annotated edition of the verse catalogue of Syriac authors by ʿAbdishoʿ). The three-volume Catalogue of the Hebrew and Syriac mss. in the Vatican Library was also compiled by him in conjunction with Stephanus Evodius (1756–9; the Syriac mss. are described in vols. 2–3). He was also the editor of the three volumes of Greek texts attributed to Ephrem (1732, 1743, 1746; the three Syriac volumes were edited by P. Mubārak/Benedictus). A list of his extensive published literary output was drawn up by A. Mai, in Scriptorum Veterum Nova Collectio III.2 (1828), 165–68; this includes the many works left unpublished, or unfinished at his death (he had planned several further volumes of the Bibliotheca Orientalis); some of these were published posthumously (e.g., his monograph on the Patriarchs of Antioch, 1881), while others perished in a fire several months after his death. Ms. Vat. Syr. 389 is an autograph Syriac grammar (1707). He also played a central role in the Synod of Mount Lebanon (1736).