His father, Tommaso Casanatta, was a member of the supreme council of the Kingdom of Naples. Girolamo studied law at the university of his native town and practised in the courts for some time. Eventually he gave up the promises of a secular career and entered the service of the Church, in deference to the advice of Cardinal Pamphili whom he had met on a visit to Rome. When that cardinal became pope as Innocent X, Casanata was made private chamberlain and soon advanced rapidly in the ecclesiastical career, becoming in turn Governor of Sabina, Fabriano, Ancona, and Camerino. In the last-named city he became a close friend of its bishop, Emilio Altieri, afterwards Pope Clement X. In 1658 Pope Alexander VII sent him as inquisitor to Malta, whence he was shortly recalled to Rome and made prelate of the Consulta and active member of the courts known as the Segnatura di Grazia and the Segnatura di Giustizia.
He was Consultor of the Congregation of Rites and of Propaganda, and governor of the conclave that chose the successor of Alexander VII; under Clement IX he was made assessor of the Holy Office (Congregation of the Inquisition). He was appointed secretary of the Congregation of Bishops and Regulars by Clement X, and 13 June 1673, was named Cardinal-Deacon of the Title of Santa Maria in Porticu, and later (1686) Cardinal-Priest of the Title of San Silvestro in Capite. In 1693 Innocent XII bestowed on him the office of Librarian of the Vatican (Bibliotecario di Santa Romana Chiesa). On his death-bed he was assisted by two Dominicans, Father Antonin Cloche the general of the order, and Antoine Massoulié. He was buried in the Basilica of St. John Lateran, though his heart was deposited in Santa Maria sopra Minerva, the church of the Dominicans, to whom he was always warmly attached, and who looked on him as their benefactor.
He held many offices, in which it was necessary that he study profoundly the numerous doctrinal, disciplinary, and political questions brought before the Holy See in the latter half of the seventeenth century, among them controversies concerning Quietism (Miguel de Molinos, Fénelon, Madame Guyon), the Gallican Liberties, the right of Régale, the Four Articles of 1682, the Chinese Rites controversy between the Jesuits and the Dominicans and other orders.
His chief service to learning, especially the theological sciences, was the Casanatense Library (Biblioteca Casanatense) founded and endowed by him. While living he had collected a library of about 25,000 volumes; this he left to the convent of the above-mentioned Dominican basilica Santa Maria sopra Minerva, together with an endowment fund of 80,000 scudi (almost as many dollars), to provide for the administration of the trust and for the acquisition of new books. This convent was at that time the home of the College of St. Thomas, which in the 20th century would be relocated at the convent attached to the Church of Saints Dominic and Sixtus and grow into the Pontifical University of St. Thomas Aquinas, Angelicum.
In 1655 the same convent had inherited the library of Giambattista Castellani, chief physician of Gregory XV, with 12,000 scudi for the erection of a suitable edifice. Cardinal Casanata, moreover, ordered that the new library should be accessible to the public six hours daily, excepting feast-days. In addition to the library staff he provided for a college (theologi casanatenses) of six Dominicans of different nationalities (Italian, French, Spanish, German, English, Polish). Each of them must previously have received the degree of Doctor from one of the most famous universities of Europe. Aided by the resources of the library, they were to devote themselves to the defence and propagation of Catholic doctrine.
Moreover, two professors were to expound regularly the text of St. Thomas Aquinas (Summa Theologica and other writings). In other words, by means of the new library, he had created at Rome another centre of intellectual activity (see Minerva, 1892–93, II, 622). After the loss of the temporal power (1870) the library was declared national property, but the Dominicans were left in charge until 1884. Amongst the library's possessions are 64 Greek codices (15 of them the gift of Casanata), and 230 Hebrew texts (rolls and books), among which are 5 Samaritan codices. The incunabula (books printed before 1500) number 2036; there is also a large collection of Roman governmental proclamations (bandi, editti) from 1500 to 1870, comedies of the seventeenth and eighteenth centuries, etc. Father Antonin Cloche the General of the Dominicans placed in the library a statue of Cardinal Casanata, the work of the sculptor Le Gros. An inscription records the formal permission of Clement XI to preserve there the books of what were considered heretical authors.
The Casanatense Library still preserves 1125 manuscript volumes of opinions, reports, and statements (voti, relazioni, posizioni) concerning matters treated in the various Congregations to which Casanata belonged. His curial duties did not prevent him from taking an interest in letters and the sciences. He was on friendly terms and corresponded with the learned men of his day. Among those whom he encouraged most was Zaccagni, whom he induced to publish a collection of materials for the ancient history of the Greek and Latin Churches, Collectanea monumentorum veterum Ecclesiæ græcæ et latinæ (Rome, 1694, 4to).
- This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913). "Girolamo Casanata". Catholic Encyclopedia. Robert Appleton Company. cites:
- Touron, Hommes illustres de l'ordre de saint-Dominique (1743–49), IV, 534 sqq.;
- Biblioteca Casanatense - home page (Italian)