His chief work is
Italia sacra sive de episcopis Italiæ (9 vols, 1643–1662), an account of all the episcopal sees of Italy, with lists of the bishops and a great deal of information regarding the
history of Italy. In compiling this work, Ughelli frequently had to deal with matters not previously treated by historians; as a result, the
Italia sacra, owing to the imperfections of historical science in Ughelli's day, especially from the point of view of criticism and
diplomatics, contains serious errors, particularly as the author was more intent on collecting than on weighing documents. Nevertheless, his work with all its imperfections was necessary to facilitate the labours of critical historians of a later day, and is consulted even now. In the last volume of the
Italia sacra he published various historical sources until then unedited. Ughelli's achievement deserves the highest praise. It was an astonishing performance, which did something to foster Italian self-consciousness, though this was not Ughelli's aim; and of course it led to similar books being compiled for every other large country in Europe:
Gallia Christiana, the French equivalent of Ughelli's undertaking, appeared twelve years later while
Henry Wharton's
Anglia sacra was only published in 1691. Ughelli's work was abridged by Giulio Ambrogio Lucenti (Rome, 1704) and republished, with corrections and additions, by
Nicola Coleti (10 vols, Venice, 1717-22). Coleti brought the information down to his own day. Since then, although the early history of some of the dioceses has been reinvestigated in a thoroughly scholarly way, nothing of a general kind has been attempted.
Giovanni Giacinto Sbaraglia's
Supplementum ad Italiam sacram Ferdinandi Ughelli was left unpublished, while Nivardo del Riccio's new edition of Ughelli's work never came to fruition.
Gaetano Moroni in his dictionary (Venice, 1840-61) is entirely dependent on Ughelli when traversing similar territory; Giuseppe Cappelletti's ''Le chiese d'Italia'' (Venice, 1844–79) paraphrases Ughelli in Italian and for all practical purposes may be forgotten. Ughelli's work exerted a great influence on
Gams'
Series episcoporum ecclesiæ catholicæ (1873-86) and on
Eubel's
Hierarchia Catholica Medii Aevi (1913–1967). Among his other writings are: •
Cardinalium elogia ex sacro ordine cisterciensi (1624): writings in praise of
cardinals of his order and the papal privileges granted to it; •
Columnensis familiæ cardinalium imagines (1650): biographies of cardinals of the
Colonna family. • genealogical works on the Counts of Marsciano (1667) and the Capizucchi (1653); •
Aggiunte ("additions") to the
Vitae et res gestae pontificum by
Alphonsus Ciacconius. Ughelli corresponded with several important scholars, including
Leo Allatius,
Constantino Cajetan,
Luke Wadding,
Karel de Visch and Pierre de Sainte-Marthe (the son of the
Maurist scholar
Scévole). Pierre, together with his brother Louis, compiled in 1656 the
Gallia Christiana, the French equivalent of Ughelli's work on the Italian dioceses. ==Notes==