Hippolyte Delehaye (1859-1941) was the most prominent Bollandist of the 20th century. His work includes the critical editions with commentaries of the Synaxarium of Constantinople, the Hieronymian Martyrology and the Roman Martyrology as well as books about critical methodology in hagiography (Les légendes hagiographiques, 1905), historical syntheses (Les origines du culte des martyrs, 1912; Sanctus. Essai sur le culte des saints dans l'Antiquité, 1927) and monographs about the passions of the martyrs and their cults. His fellow Jesuit Paul Peeters (1870-1950) was a pioneer in the study of the Oriental hagiography. Vol. IV of the Acta Sanctorum of November (1925) reflects his extraordinary linguistic capacities with texts in Coptic, Arabic, Ethiopic, Syriac, Armenian and Georgian.