JEILER, IGNAC. - Franciscan theologian and medievalist, born at Havixbeck in Westphalia on 4 Dec. 1823, died at Quaracchi on 4 Dec. 1904. He studied at Münster and Paderborn. He became a Franciscan friar in 1845 and a priest in 1848. Through his fruitful apostolate and rigorous ascetic life he earned great esteem, while in teaching he developed a wide theological and philosophical culture. After the Vatican Council he rendered great service to many bishops against the teachings of Döllinger and the Old Catholics, as he had previously done at the Sacred 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. Beckx, he brought to completion the monumental critical edition of the works of St. Bonaventure (10 vols. fol., Quaracchi 1882–1902), with rich illustrations.
He also worked on the collection of texts and historical documents *Analecta Franciscana* and the *Acta Ordinis Fratrum Minorum*. He collaborated on various journals and encyclopedias. He published: *De humanae cognitionis ratione anecdotae quaedam seraphici doctoris s. Bonaventurae et nonnullorum ipsius discipulorum* (Quaracchi 1883); *S. Bonaventurae principia de concursu Dei, generali ad actiones causarum secundarum collecta et s. Thomae doctrina confirmata* (ibid. 1897), and many other writings on hagiography and ascetics.