The absence of any adequate modern biography of Mabillon has long left a deplorable gap in the history of French scholarship. Almost immediately after his death his intimate disciple, Dom Thierry Ruinart, wrote a short life which must always remain essential for any estimate of its subject's character, and a more formal notice found its place in Dom Tassin's history of the Maurists. After that, no work of any originality or insight appeared until 1879, when a well-documented study of Mabillon's early life and some of his work was published in a most inaccessible fashion by H. Jadart, who continued his patient investigations for another thirty years. Then, in 1888, Emmanuel de Broglie produced his classical picture of the society of St. Germain-des-Prés and the journeys of Mabillon which, though a work of genuine scholarship and high literary charm, was extremely selective and made no attempt to cover the whole of Mabillon's life and work. De Broglie's volumes, however, soon followed by a similar work on Montfaucon, by their very excellence deterred would-be biographers until in the early years of the present century Dom P. Denis began to make preparatory soundings among the mass of Maurist documents with a view to writing a formal history, which must have contained a long account of Mabillon. His labours issued in a number of valuable articles in the Revue Mabillon, but he died with his main task unaccomplished. Meanwhile Dom Henri Leclercq contributed to the Dictionnaire d'archéologie chrétienne et de liturgie an article, as long as a short book, on Mabillon, as well as numerous other articles on topics connected with his works, but it was not generally known that during the last years of his life, in what time that indefatigable worker could steal from compiling single-handed the last volumes of his great Dictionnaire, he had written what was at least the first draft of a full-scale biography. He succeeded, as is well known, in finishing his encyclopedia a few months before his death, and he also despatched the manuscript on Mabillon to his Paris publisher, but, for an unexplained reason, publication was long delayed and it was only a year ago that the second volume appeared. It is nowhere stated what editorial changes have been made, though it is implied that there has been some abbreviation.