Mai, Angelo a noted Roman Catholic prelate, and one of the most distinguished scholars of the 19th century, was born at Schilpario (province of Bergamo), Italy, March 7, 1782. As a youth he arrested the attention of his instructor, the ex-Jesuit father Lewis Mozzi de' Caspitani, by the unusual taste and capacity which he displayed for classical learning. The father, determined to lead Angelo's inclination towards the service of the Church, finally induced him to enter, in 1799, the novitiate of the Society of Jesus, which, although elsewhere suppressed, the Duke of Parma, with the sanction of Pius VI, was just re-establishing at Colorno, a small city of his duchy. In this community Mai resided till the provisional restoration of the society in Naples (1804), whither he was sent as Professor of Greek and Latin literature. About the end of 1805 he was transferred to Rome for the completion of his theological studies, and soon afterwards to Orvieto, and was there admitted to priest's orders. It was at this place that he acquired great familiarity with the Hebrews language, his accurate knowledge of palaeography, and his skill in deciphering ancient manuscripts. He returned to Rome in 1808, just about the time when the contest of Pius VII with Napoleon was reaching the crisis; an order issued by the viceroy, commanding all subjects of the kingdom of Italy to return to their respective provinces, had compelled him to change his residence once again. Happily for the interests of literature, he settled at Milan. The Ambrosian Library of that city had long been known as rich in manuscripts of the highest interest — the remnant of the treasures of the old monastic libraries, especially those of Bobbio and Lucca, and of some of the suppressed Benedictine convents of the Protestant cantons of Switzerland. Many of its best treasures had been made public by Muratori, Mabillon, and the Benedictine editors; but there yet remained a department entirely unexplored, which Mai soon appropriated to himself, and which has since come to be regarded as exclusively his own-that of palimpsest or re-written manuscripts, in which the original writing has been effaced in order to make room for a later work written over it. Mai was admitted an associate, and eventually a doctor of this celebrated library, and labored in this novel editorial career with a zeal and success not unworthy of the traditional glories of his country. From the Society of Jesus, to which he had not yet avowed himself, he now withdrew, with the consent and approval of the authorities at Rome. His first essay as an author was a Latin translation (with a commentary) of Isocrates, De Permutatione (1813), the original of which had been published by a Greek named Andrew Mustoxidi in the previous year; but this was only the prelude of his far more remarkable successes in the decipherment and publication of palimpsest manuscripts. Up to this period, with the exception of Küster and Wetstein's readings of the Old and New Testament from the Codex Ephremi. Knittel's portions of the Gothic Bible of Ulphilas, Peter Bruns's fragment of the ninety-first book of Livy, and Barrett's palimpsest of the Gospels, palimpsest literature was entirely untried. Within a few years Mai deciphered and published from palimpsest sources writings of several classical authors, besides two works then supposed to be by Philo Judaeus, but afterwards recognized as the productions of Georgius Gemistus. In 1819 Mai was called to Rome as chief keeper of the Vatican Library, canon of the Church of St. Peter's, and domestic prelate of the pope, Pius VII. Here he continued the publication of palimpsest manuscripts, and in 1820 brought out the work by which he is best known out of Italy — a large and interesting portion of the long lost
De Republica of Cicero, the fragments of which he arranged with consummate skill in their respective order, and interwove with all the known extracts of the work which had been preserved in the collections of ancient authors. The whole text he illustrated by a critical commentary of exceeding interest, which at once established his reputation as one of the first scholars of the age.
From these comparatively desultory labors he turned to a project not unworthy of the palmiest days of Italian editorship. Selecting from the vast and till then imperfectly explored manuscript treasures of the Vatican, he prepared his Scriptorum veterum Nova Collectio e Vaticcanis Codicibus edita (Rome, 1825, and later, 10 vols. 4to), on the plan of the various Anecdota, published under different titles by Mabillon, Pez, Montfaucon, Muratori, and others. It is a work of immense labor and research, and of a most miscellaneous character — Greek and Latin, sacred and profane, theological, historical, patristical, and philosophical. Next, he published Classici Scriptores ex Codicibus Vaticanis editi (completed in 1838, in 10 vols. 8vo), which included some of the author's earlier publications (especially the De Republica); although, with the exception of about two volumes, its contents were entirely new Scarcely was this collection finished when he entered upon the preparation of the Spicilegium Romanum (1839-44, 10 vols. 8vo), equally interesting and various in its contents, and a fourth collection entitled Nova Patrum Bibliotheca (1845- 53, 6 vols. 4to), thus completing a series unparalleled since the days of Muratori, and, indeed, far more extraordinary than the older collections, from the circumstance that it was compiled from the mere gleanings which had escaped the research of the earlier generations of editors and collectors. In addition to all these labors, and while they were still on his hands, he commenced an edition of the well-known Codex Vaticanus of the Old and New Testament, with various readings and prolegomena, which, however, he never entirely completed; or if he did, as some suppose, he destroyed a greater part of his manuscript on the Old Testament, lest it should ever see the light of day in an incomplete and imperfect state. The text of the New Testament was published in 1858, and in a thoroughly revised form in 1859, under the title Nov. Test. ex vetustissimo codice Vat., secundis cursis editumn studio Angeli AMaii; but even in a revised form the work does not deserve the name of Mai on its titlepage. Comp. Kitto, Journ. Sac. Lit. 1859 (Oct.), p. 166 sq.
While engaged in these vast literary enterprises Mai held the laborious and responsible post of secretary of the Propaganda, to which he had been appointed in 1833; and it was observed with wonder that his other engagements were never suffered to interfere with the duties of the secretaryship. In 1838 he was rewarded for his great services to the Church with the cardinal's hat, at the same time with his friend and successor in the Vatican Library, Mezzofanti; and soon afterwards was appointed to several important and confidential offices in the Roman court, chiefly of a literary character. He was named successively prefect of the Congregation for the Supervision of the Oriental Press; prefect of the Congregation of the Index; and prefect of the Congregation of the Council of Trent. In 1853 he was appointed to the still more congenial post of librarian of the Roman Church. He died September 9, 1854.
"Cardinal Mai's abilities as an editor," says his biographer in the English Cyclopaedia, "were of the very highest order. While his collections comprise an infinite variety of authors of every age, of every country, of every variety of style, and in every department of literature, he appears in all equally the master. Whether the subject be theology, or history, or law, or languages, or general literature, his learning is never at fault, and his critical sagacity never fails. In the many delicate and difficult questions which so often arise — in assigning an anonymous manuscript to its true author, in collecting fragments of the same work and dovetailing them together into intelligible order, in selecting from a heap of unknown materials all that is unpublished, and deciding upon the question of its genuineness or its intrinsic value — in a word, in all the thousand investigations which fall to the lot of a critical editor treading upon untried ground, he possessed a skill and acuteness which can hardly be described as other than instinctive, and which, taking into account the vast variety of subjects which engaged him, must be regarded as little short of marvelous. The private character of Cardinal Mai has been well described as the very ideal of a Christian scholar. Earnestly devoted to the duties of his sacred calling, he yet loved literature for its own sake also, and he was ever foremost in every project for its advancement. He was a member of all the leading literary societies of Italy, and not unfrequently read papers in those of Rome and Milan. His charities were at all times liberal, and, indeed, munificent; and at his death he bequeathed the proceeds of the sale of his noble library to the poor of his native village of Schilpario. A monument has been erected to his memory in the church of St. Anastasia, from which he derived his title as cardinal." See Mutti, Elogio di Angelo Mali (1828); Rabbe, Biog. Univ. des Contemporains; Hoefer, Nouv. Biog. Generale, 32:857 sq.; English Cyclop. s.v.; Wetzer und Welte, Kirchen-Lexikon, vol. 12, s.v.