HAGIOLOGY, that branch of the historical sciences which is concerned with the lives of the saints (Gr. aywos, saint, Xhyos, discourse). If hagiology be considered merely in the sense in which the term has come to be understood in the later stages of its development, i.e., the critical study of hagiographic remains, there would be no such science before the 17th century. But the bases of hagiology may fairly be said to have been laid at the time when hagiographic documents, hitherto dispersed, were first brought together into collections. The oldest collection of this kind, the 7—Co apxafwv ,uaprvpLwv of Eusebius, to which the author refers in several passages in his writings (Hist. Eccl., v. proem 2; V. 20, 5), and which has left more than one trace in Christian literature, is unfortunately lost in its entirety.
The Martyrs of Palestine, as also the writings of Theodoret, Palladius and others, on the origins of the monastic life, and, similarly, the Dialogues of St. Gregory (Pope Gregory I.), belong to the category of sources rather than to that of col lections. The In gloria martyrum and In confessorum of Gregory of Tours are valuable for the sources used in their compilation. The most important collections are those which comprise the Acts of the Martyrs and the lives of saints, arranged in the order of the calendar. In the Greek Church these are called menologies (from Gr. yip, month, Xhyos, discourse), and their existence can be traced back with certainty to the 9th century (Theodore of Studium, Epist. i. 2). One of them, the menology of Metaphrastes, compiled in the second half of the loth century, enjoyed a universal vogue (see SYMEON META PHRASTES) . The corresponding works in the Western Church are the passionaries or legendaries, varieties of which are dispersed in libraries and have not been studied collectively. They generally draw from a common source, the Roman legendary, and the lives of the local saints, i.e., those specially honoured in a church, a province or a country.
The actual founder of hagiologic criticism was the Flemish Jesuit, Heribert Rosweyde (d. 1629), who, besides his important works on the martyrologies (see MARTYROLOGY), published the celebrated collection of the Vitae patrum (Antwerp, 1615), a veritable masterpiece for the time at which it appeared. It was he, too, who conceived the plan of a great collection of lives of saints, compiled from the manuscripts and augmented with notes, from which resulted the collection of the Acta sanctorum (see FiOLLANDISTS). This last enterprise gave rise to others of a similar character but less extensive in scope.