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, he won great esteem for his fruitful apostolate and his life of rigid asceticism, while in teaching he acquired a vast theological and philosophical culture. After the Vatican Council he was of great help to many bishops against the doctrines of Dillinger and of 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 confreres G. Deimel, Q. Müller and B. Beckte, he brought to completion the monumental critical edition of the works of St. Bonaventure (10 vols. in-fol., Quaracchi 1882-1902), with learned annotations.
He also worked for the collection of historical texts and documents Analecta Franciscana and for the Acta Ordinis Fratrum Minorum. He collaborated on 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 ascetics.