Hippolyte Delehaye - The Work of the Bollandists through Three Centuries, 1615-1915 (1922)
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Hippolyte Delehaye - The Legends of the Saints: An Introduction to Hagiography (1906)
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As a companion to the last post about martyrs here is a history of the Bollandists, a long-lived group dedicated to compiling and evaluating original documents related to saints and martyrs. It sounds somewhat routine but what was originally planned as 18 volumes is now running 80 and not yet finished (after four centuries!). Perhaps more importantly one result of this work (called the Acta Sanctorum) has been to trim apocryphal and unreliable stories and even persons. For more see the extensive entry in The Catholic Encyclopedia.
Delehaye covers the history as indicated in the title and is well-written (at least in translation) and fairly quick moving. Those of us fascinated by book hunting, philology, textual editing, religious legends and the like will be drawn to this. I doubt anybody else has read this far into the post.
Hippolyte Delehaye (1859-1941) was a Jesuit scholar and himself a member of the Bollandists. Though he's described as a quiet scholar, in 1916 he was arrested for anti-German propaganda. His work was highly regarded and he received numerous honors, including an honorary doctorate from Oxford. There's an extensive appreciation and overview by Thomas J. Heffernan in Medieval Scholarship: Biographical Studies on the Formation of a Discipline (1998, edited by Helen Damico).