Roman Catholic Cardinal. Born into a profoundly Christian family, the son of a veterinarian, who being a good friend of the Redemptorists of the monastery of Madonna dell'Olmo of Montecchio d'Emilia had a good part of their library was placed in his home upon the closure of their convent in 1859, Giovanni Mercati was the third of seven children of whom three would eventually become priests. Rising to become an amusingly capable paleographer; an expert of program schedules; a thoroughly educated and tireless researcher; librarian for sixty four years, first at the Ambrosian Library, then at the Vatican; patron of the Papal Library, such talented was he that he remains hailed as the "most learned prelate to be elevated to the sacred purple" in the twentieth century. Once quoted as saying, "I'm always ready to learn", Mercati was ordained priest on September 21, 1889 in Reggio Emilia. Frequenting the public sessions of the Accademia di Conferenze Storico-Giuridiche, he was admitted to the Vatican Library in February 1890. Rendering obligatory military service in Florence as between 1891 and 1893, he successively worked in the Ambrosian Library in Milan from 1893 till 1898 and eventually at the Vatican Library from 1898 until 1919, after being called by Pope Leo XIII in October 1898. A member of the Historical-Liturgical Commission, established by the Pope, he was named consultor of the Pontifical Commission for Biblical Studies on January 31, 1903 and later domestic prelate of His Holiness with the title of Monsignor on August 2, 1904. Furthermore he was also nominated as 'socio corrispondente' of the Pontifical Roman Academy of Archeology on May 11, 1917 and prefect of the Vatican Library on October 23, 1919. That same year, Mercati was created cardinal deacon in the consistory of June 15, 1936 by Pope Pius XI with the deaconry of San Giorgio in Velabro. Retaining his position as librarian and archivist of the Holy Roman Church until his death, Mercati passed away suddenly of a heart attack on August 23, 1957, at the venerable age of ninety inside the Vatican City. In accordance with his wishes, he was buried in his deaconry next to his brother Monsignor Angelo, whose remains he had transferred in his personal tomb which he had erected during his lifetime. An explosion of a car bomb parked close to the Basilica at midnight on July 27, 1993, left the twelfth century portico almost in total collapse and blew a large opening into the wall of the main basilica, damaging severely Cardinal Mercati's tomb. While the explosion caused no fatalities, serious damage was also caused to the residence of the Generalate of the Crosiers, the Canons Regular of the Order of the Holy Cross, next door. The church as well as Mercati's funeral monument were eventually restored.