ANGELO, a cardinal of the Roman Church, was born 7th March 1782, at Schilpario, a village of the province of Bergamo, in the Milanese territory. His parents were of the humblest peasant class; and he was placed, along with the other boys of the village, at the parish school, for the purpose of being initiated in the usual branches of elementary education. At this time, however, in consequence of the recent suppression of the Jesuit Society, and the dispersion of its members, a considerable number of ex-Jesuit priests were employed in the ordinary duties of the mission throughout Italy. One of these, Father Lewis Mozzi dei Capitani, a Milanese, who resided near Schilpario, was early struck by the remarkable abilities of Angelo Mai, and himself undertook to instruct him in Latin, Greek, and mathematics. About this time the Duke of Parma permitted the Jesuits to re-establish themselves at Colorno, in the duchy of Parma; and Mai, who was then about seventeen, accompanied his patron, Father Mozzi, to the college there opened; and with four youths of his native village, entered the novitiate of the society in 1799. He completed the novitiate in 1801, but remained at Colorno until 1804, when the society was more solemnly (though still only provisionally) re-established in the kingdom of Naples. To the college there founded Mai was sent as professor of Greek and Latin; but after somewhat more than a year and a half, he was transferred to Rome, when he completed his theological studies. Thence he was removed to Orvieto, where the bishop, M. Lambruschini, had invited the Jesuits to open a house. At Orvieto he was promoted to priest's orders; and remained partly engaged in teaching, partly in prosecuting his private studies, till 1808, when he was recalled to Rome. In that year, however, on the occupation of the Papal States by the French, an order was issued by the viceroy of Italy, requiring all natives of the kingdom of Italy to return to their respective provinces, and Mai was obliged to repair to Milan. As the Society was still unrecognised in the kingdom of Italy, Mai was compelled to seek for other occupation, and assumed the functions of a secular priest. After a time, through the influence of his first protector, Padre Mozzi, he was named an associate of the Ambrosian College, and soon afterwards a doctor of the Ambrosian Library. It is to his connection with this library that he is mainly indebted for his literary reputation.

Next to the unrivalled collection of the Vatican, the MS. treasures of the Ambrosian Library have long been celebrated in Italy for their number and importance. Enriched by contributions from the libraries of Bobbio, Lucca, Monte Cassino, and other great monasteries, the Ambrosian collection is now the depository of a large proportion of the literary treasures of the learned Benedictines of Italy; and although many of its MSS. had already been published or collated by the industrious editors of the seventeenth and eighteenth centuries, yet at the time when Mai was enrolled as an associate, it still contained enough to stimulate his curiosity and to exercise his learning. He had early acquired a taste for this branch of study under his first masters in the Jesuit Society, among whom were two learned Spanish fathers of some reputation in that department; and he now devoted a considerable time to a careful exploration of the Ambrosian MSS. His first publication was a Latin translation (accompanied by a critical commentary) of the recently discovered work of Isaacus, De Permutatiorum; but he speedily relinquished the more beaten track of an ordinary editor or translator, and devoted himself to the then almost unknown department of palimpsest; or re-written MSS.—a class in which the Ambrosian Library is peculiarly rich. Up to this time but two or three palimpsest fragments had been deciphered and made public. In the course of a few years Mai was enabled to print two volumes of meditated fragments of Cicero's Orations, some orations of Lysimachus and Isaeus, an interesting fragment of Plautus's lost comedy the Vidularia, and, above all, a large collection of the letters and other writings of Cornelius Fronto, the preceptor of Marcus Aurelius. The MS. from which these relics of Fronto were recovered had formerly belonged to the monastery of Bobbio, and was a translation of a part of the Acts of the Council of Chalcedon, written upon a series of palimpsest leaves, made up partly of an ancient MS. of Pliny the Younger, partly of an old commentator on Cicero, partly of some of the works of Lysimachus, and partly of letters of Fronto addressed to Antoninus Pius, Marcus Aurelius, Lucius Verus, and other friends,—all in a very disordered and mutilated condition, but yet sufficiently perfect to excite the curiosity of the learned throughout Europe. The most interesting circumstance, however, of the discovery is, that when Mai, some years later, was removed to the Vatican Library, he had the good fortune to find the remainder of this very palimpsest translation of the Acts of Chalcedon, the counterpart of the Ambrosian palimpsest, containing above a hundred additional letters of the same correspondence.

Meanwhile, the Jesuit Society had been formally revived by Pope Pius VII. on his restoration in 1814. But the services of Mai in his new position were so highly appreciated that, as he had never taken the solemn vows of the Order, he was induced to remain a member of the secular clergy. In 1819 he was invited to Rome to fill the office of chief keeper of the Vatican Library. Soon after his installation in this honourable and congenial office, he discovered that a MS. of St Augustine's Enarrationes in Psalmos was a palimpsest, the original of which had been no other than the long-sought work of Cicero De Republica. The commentary itself, unfortunately, was imperfect. It extended only from the 119th to the 140th psalm (the commentary on the ten remaining psalms being deficient); and even in the portion which remained there were gaps to the amount of sixty-four pages. Nevertheless, the skill and ingenuity of Mai recovered from these confused and obliterated fragments about one-fourth of the entire work, with which he interwove, in the edition which he published (Rome 1822), all the existing fragments of the original, collected from the numberless writers, sacred and profane, through whose writings they are scattered.

The design of the pope, however, in appointing Mai to the charge of the Vatican Library had been to engage him in a formal and systematic exploration of its contents, with a view to the publication of the most important remains of classical literature which still remain locked up in that great treasure-house. Mai, extending the plan, resolved to comprise in his collections the unpublished sacred as well as profane remains of the Vatican MSS., and, leaving to future scholars the task of critically editing, commenting, and translating, to secure for the world, in miscellaneous Collectanea similar to those of Muratori, Mabillon, Montfaucon, and their fellow-labourers, all that was really important among its edited MSS. in every department of literature. On this plan he commenced, in 1825, a magnificent 4to publication,—Scriptorum Veterum Nova Collectio et Vaticanis Codicibus Editæ,—which extended to 10 volumes, and comprises a vast number of unpublished remains of the Greek and Latin writers, sacred and profane. Several of the volumes are occupied with patristical remains. The second, which is almost entirely from a palimpsest source, contains an immense number of fragments of the lost books of the historians,—Polybius, Diodorus Siculus, Dionysius of Halicarnassus, Dion, Appian, and others, even so late as Dexippus and Eumarius.

In 1833 M. Mai was transferred from the office of Vatican librarian (in which he was succeeded by the celebrated linguist Mezzofanti) to that of secretary of the Propaganda; but he still continued his literary labours. He followed up the Vaticana Collectio by another collection in 8vo, equally miscellaneous, and indeed entirely similar in plan,—Classici Auctores et Codicibus Vaticanis Editi, 10 vols. 8vo Malano (1828–35). In the year in which this work was brought to a close he was elevated to the cardinalate, and soon afterwards was named prefect of the Congregation of the Index, and of that of the Council of Trent, and eventually cardinal librarian of the Roman church.

The Classici Auctores was succeeded by a similar miscellany, but containing a larger amount of matter, Speciellum Romanum, 10 vols. 8vo (1839–44). This collection, besides Greek and Latin writers, comprises also a few interesting Italian works, chiefly historical and biographical. His last publication was in 4to, Nova Patrum Bibliotheca (6 vols. 1845–53). It is almost exclusively patristical, and contains many highly important works, forming an indispensable supplement to almost all the existing patristical collections. Cardinal Mai had also undertaken to edit the celebrated Biblical Codex Vaticanus, and actually printed the text at the Propaganda press. He delayed its publication, however, with the intention of prefixing to the text an elaborate critical and historical introduction; but to the infinite disappointment of the learned, he died, leaving this great work incomplete, and indeed does not even appear to have made any progress in the preparation for it. Since his death, which occurred in his seventy-fourth year, at Albano, September 8, 1854, no trace of the expected biblical dissertations has been discovered. It is highly probable that the anxious and unsettled condition of political affairs at Rome during the years preceding his death, deprived him of the leisure or the spirit necessary for so laborious an undertaking. From the very nature of Cardinal Mai's collections it will be understood, that in very many of the works which he printed he contented himself with the mere rough work of publication. But in those which he undertook to edit critically, and especially in the De Republica, he appears as a master in the art. Even those works the text of which alone he printed, are accompanied by learned and judicious prefaces, which exhibit an amount of erudition such as few modern scholars can claim. His library was one of the most complete private collections in Rome. At his death he directed that it should be offered at half its estimated value to the Vatican Library, and that the proceeds of the sale should be applied to the use of the poor of his native village of Schilipario.