KELLNER, KARL ADAM HEINRICH. - Patrologist and liturgist, b. at Heiligenstadt am Eichfeld (Prussian Saxony) on 26 Aug. 1837, d. at Bonn on 6 Jan. 1915. After becoming a priest, he devoted himself to pastoral care; he was then professor of theology at the Seminary of Hildesheim (1867–74) and, from 1882 until his death, professor of patrology, liturgy, and catechetics at the University of Bonn.
Among his writings, noteworthy are: the translation of the works of Tertullian (1882) and Ausgewählte Schriften des Sept. Tertullianus (2 vols., 2nd ed., 1912). His most valuable work is Heortologie oder das Kirchenjahr und die Heiligenfeste in ihrer geschichtlichen Entwicklung. Three editions appeared (Freiburg im Br. 1900, 1906, and 1911; Italian trans. by A. Mercati, L'anno ecclesiastico e le feste dei santi nel loro svolgimento storico, 2nd ed., Rome 1914); the work elicited the most flattering approval (cf., for example, Analecta Bollandiana, 21 [1902], p. 95). In it K. indeed gathered, by sound method, and examined extensive material for the history of the liturgical year and its principal feasts.