THEINER, Augustin. – Priest and historian, b. at Breslau on 11 Apr. 1804, d. at Civitavecchia on 8 Aug. 1874. Son of a German father and a Polish mother, he had as his elder brother Johann Anton T., who persuaded him to devote himself to legal and historical studies.
He collaborated with his brother on the part concerning the origin and historical development of ecclesiastical celibacy in the work published by the latter in 1828, and having taken degrees in philosophy and jurisprudence he devoted himself to the study of canon law. For an erudite monograph on the formation of the decretals of Gregory IX (*Commentatio de Romanorum Pontificum epistolarum decretalium antiquis collectionibus et de Gregorio IX Pontificis Maximi decretalium codice*, Leipzig 1829), he was offered a university chair at Berlin, which T. refused in order to visit libraries, archives, and museums throughout Europe in search of study materials. In Paris he met the Maronite scholar, and on the advice of the Bishop of Orléans, Beauregard, and of Möhler, he came to Rome in 1833 and shut himself up in the Seminary of S. Eusebio. He made a submission on the errors propagated in the work on ecclesiastical celibacy and gave an account of his conversion in a work published, also in Italian, in 1834 under the title *Il Seminario ecclesiastico o gli otto giorni a S. Eusebio in Roma*. Ordained priest, in 1839 he entered the Congregation of the Oratory and in the library of S. Maria Nuova in Vallicella he resumed his historical studies, never abandoned in the preceding years. As early as 1836 he had published the *Disquisitiones in praecipuas canonum et decretalium collectiones*; and later other writings such as that on the condition of Catholicism in Poland and Russia (*Die neuesten Zustände der katholischen Kirche in Polen und Russland*, 1841), or on particular events of religion and the Church in the Germanic countries. In 1849 he polemicised with Rosmini and criticised his thesis on the election of bishops as maintained in *Le Cinque Piaghe della Chiesa* (*Lettera storico-critica intorno alla elezione dei vescovi mediante il clero ed il popolo*, Naples 1849).
Much beloved by Pope Pius IX, T. was entrusted by him with the task of composing a history of the pontificate of Clement XIV to counter the recently published work of Crétineau-Joly. Appointed by the Pope coadjutor of the Prefect of the Vatican Archives with right of succession in March 1851, he was able to gather and study the documents necessary for that work, which was printed in 1853, causing a great stir because of its hostility to the Jesuits and provoking numerous refutations, more exact and better founded, among which were those of G. Boero (v.) and F. X. Ravignan (v.). Appointed Prefect of the Archive in Nov. 1855, T. continued the *Annales ecclesiastici* of Baronius and in 1856 published three volumes bringing the narrative down to the end of the pontificate of Gregory XIII; he also prepared a new edition of the same *Annales* in 37 vols. (Bar-le-Duc 1864–83). From the papers of the Vatican Archive he drew: *Vetera Monumenta Historica Ungharian Sacram Illustrantia* (2 vols., 1859); *Polonia* (4 vols., 1860–64); *Slavi meridionali* (2 vols., 1863); *Irlanda e Scozia* (1864); *Monuments historiques rélatifs aux règnes d'Alexis Michaleovitch, Feodor II et Pierre le Grand* (1859). New controversies were aroused by the *Histoire des deux Concordats de la République française et de la République cisalpine conclus en 1801 et en 1803* (1869). Favourable to the anti-infallibilists, during the Ecumenical Council T. communicated to Cardinal Hohenlohe the internal regulations of the Council of Trent, thereby contravening official secrecy, for which Pius IX dismissed him from the prefecture. At his death there appeared at Zagreb an incomplete edition of the *Acta genuina Concilii Tridentini* (2 vols.). The scholarly output of T. is distinguished, more for the abundance of data and information than for sound criticism and historical depth, though not always fully reliable.
His brother Johann Anton, b. at Breslau on 15 Dec. 1799, d. there on 15 May 1860, was likewise a priest and writer. Ordained in 1832, two years later he was appointed extraordinary professor of exegesis and canon law at the University of Breslau. Having obtained in 1826 the doctorate in theology and canon law, he carried on an intense reformist activity with the writings: *Die katholische Kirche in Schlesien* (1826) and *Einführung der erzwungenen Ehelosigkeit bei den christlichen Geistlichen und ihre Folgen* (1828), and in the latter, drawn up in collaboration with his brother Augustin, he violently attacked ecclesiastical celibacy. Both writings were placed on the Index in 1826 and 1829 respectively. Persisting in his activity, he had to leave his chair in 1830 and became parish priest at Polsnitz, then at Grüssau and at Hundsfeld. He then openly adhered to the “German-Catholic” movement of Ronge and was excommunicated in 1845. Reduced to the lay state, he became head of the “German-Catholic” community at Breslau and soon came into conflict with Ronge, whom he attacked in 1845 in a writing likewise placed on the Index, *Reformatorische Bestrebungen in der katholischen Kirche*. From 1855 to 1860 he was secretary of the University Library at Breslau. He died without having been reconciled with the Church.