Cardinal, archivist, and librarian at the Vatican; b. Villa Gaida (Reggio Emilia), Italy, Dec. 17, 1866; d. Vatican City, Aug. 22, 1957. He was ordained in 1889; in 1893 he was called by Msgr. A. Ceriani to the Ambrosian Library in Milan. In 1898 Father Francis Ehrle, SJ, invited him to the Vatican Library as an expert on Greek MSS. On Oct. 23, 1919, he was appointed prefect of the Vatican Library, and on June 18, 1936, he became archivist and librarian of the Roman Catholic Church and was created cardinal deacon with the title of S. Giorgio in Velabro. Recognized as one of the most learned scholars of the times, he was equally skilled in Greek and Latin patristics, in the theology and literature of Byzantium, as well as in classical, medieval, and Renaissance literature. He is the author of more than 400 works in these various fields; among his more important contributions are the following: "D'un palimpsesto Ambrosiano contenente i Salmi esapli …," Atti Acc. scienze Torino, 31 (1895–96) 655–676; Codices Vaticani graeci 1–329, in collaboration with F. De' Cavalieri (Rome 1923); Prolegomena de fatis bibliothecae monasterii S. Columbani Bobiensis et de codice ipso Vat. lat. 5757 (Vatican City 1934); Note per la storia di alcune biblioteche romane nei secoli XVI–XIX, Studi e Testi, 164 (Rome 1952); and four volumes of minor works, Studi e Testi, 76–79, in which all his articles before 1936 are collected. Cardinal Mercati exerted an influence on scholars throughout the world by his publications, scientific research, and competent advice; yet he was a living example of modesty and simplicity.
Bibliography: a. campana, Nel Novantesimo Anno del Cardinale Mercati 1866–1956 (Vatican City 1956), with complete bibliog. of M.'s works. h. jedin, Lexikon für Theologie und Kirche, ed. j. hofer and k. rahner, 10 v. (2d, new ed. Freiburg 1957–65) 7:303–304.