JEILER, IGNAZ. - Franciscan theologian and medievalist, b. at Havixbeck in Westphalia on 4 Dec. 1823, d. at Quaracchi on 4 Dec. 1904. He studied at Münster and Paderborn. A Friar Minor in 1845 and a priest in 1848, through his fruitful apostolate and life of rigorous asceticism he won great esteem, while through teaching he acquired a broad theological-philosophical culture. After the Vatican Council he was of great help to many bishops against the doctrines of Dillinger and the “Old Catholics,” as he had previously been to the S. Congregation of the Index in the examination and condemnation of the works of A. Günther. A victim of the Kulturkampf, he came to Italy and in 1875 joined Fr. Fedele da Fanna (v.) in the search for and description of the manuscripts of St. Bonaventure at the College of Quaracchi. After the death of Fr. Fedele in 1881, J. succeeded him and, in 22 years of assiduous work, assisted by his brethren G. Deimel, Q. Müller, and B. Beckte, completed the monumental critical edition of the works of St. Bonaventure (10 folio vols., Quaracchi 1882-1902), with learned commentaries.
He also worked on the collection of historical texts and documents Analecta Franciscana and on the Acta Ordinis Fratrum Minorum. He contributed to various journals and encyclopedias. He published: De humanae cognitionis ratione anecdota quaedam seraphici doctoris s. Bonaventurae et nonnullorum ipsius discipulorum (Quaracchi 1883); S. Bonaventurae principia de concursis Dei generali ad actiones causarum secundarum collecta et s. Thomae doctrina confirmata (ibid. 1897), and many other writings on hagiography and asceticism.