Historian, canonist; b. Wroclaw, Poland (Breslau), April 11, 1804; d. Civitavecchia, Italy, Aug. 8, 1874. Under the influence of his radically reform-minded brother Johann Anton, Theiner, a lawyer, left the Catholic Church. But his subsequent acquaintance with H. lamen nais in Paris and with Cardinal K. A. von reisach in Rome brought him to an inner conversion, and he eventually became an oratorian in Rome. He tried hard to win recognition in Curia circles with his historical works, which were marked by a pronouncedly Romanophile viewpoint. He did in fact win the favor of Pope gregory xvi and of Pope pius ix, who in 1850 appointed him to the vatican archives. With Pius IX's approval Theiner wrote Geschichte des Pontifikats Clemens XIV (Paris 1853). In this work on the pope who had suppressed the jesuits, Theiner took a stand acutely hostile to the Society of Jesus. Despite sharp criticism of Theiner, Pius IX continued to support him and in 1855 appointed him prefect of the Vatican Archives. In preparing an edition of the acta of the Council of trent, Theiner committed a serious breach of official trust; despite the papal ban on the work's publication, Theiner kept transcripts of the acta of the council in his personal possession, and they were published after his death by J. J. Strossmayer and E. Voršak (Zagreb 1874) in an edition completely unsatisfactory from a scholarly point of view. Before this, during vatican council i, Theiner informed Cardinal G. A. Hohenlohe (d. 1896) and other bishops of the opposition party about certain documents that related to the Council of Trent and that the Curia expressly wished to be kept secret. As a result Theiner was dismissed from the archives in 1870. Of his many historical works, only his editions of the sources and the three-volume continuation of baronius (Rome 1856) are of any great value.
Bibliography: Works. Geschichte der geistlichen Bildungsanstalten (Mainz 1835), with autobiography; Disquisitiones criticae in praecipuas canonum et decretalium collectiones (Rome 1836); Geschichte der Rückkehr der regierenden Häuser von Braunschweig und Sachsen in den Schoss der katholischen Kirche (Einsiedeln 1843); Vetera monumenta Hungariae, 2 v. (Rome 1859–60), Poloniae et Lithuaniae, 4 v. (Rome 1860–64), Slavorum meridionalium, 2 v. (Rome 1863), Hibernorum et Scotorum (Rome 1864); Die zwei allgemeinen Konzilien von Lyon und Konstanz und die weltliche Herrschaft des Heiligen Stuhles (Freiburg 1862); Histoire des deux concordats de la république française et de la république cisalpine conclus en 1801 et 1803, 2 v. (Bar-le-Duc 1869). Literature. a. mauri, "A. Theiner," Archivio-storico italiano 21 (1875) 350–391. h. gisiger, "Theiner und die Jesuiten," in Bilder aus der Geschichte der katholischen Reformbewegung 1.5–6 (Strassburg 1875) 213–314. f. x. seppelt, Lexikon für Theologie und Kirche, ed. m. buchberger (Freiburg 1930–38) 10:27–28. É. amann, Dictionnaire de théologie catholique, ed. a. vacant et al. (Paris 1903–50) 15.1:217–218.