Welcome to
The Digital Liber exceptionum Project

This website provides Open Access research materials from the Liber exceptionum ex libris viginti trium auctorum, a Latin florilegium compiled in 1243-46 by Guillaume de Montaigu O.Cist., an abbot of Cîteaux who resigned to spend his final years at the Cistercian abbey of Clairvaux, where he employed its important library to produce Liber exceptionum.

Ten manuscript copies are known to exist. The copy employed for this project is Paris, BnF Ms lat. 15983, which has been digitized by the Bibliothèque Nationale de France and is freely provided online.

Abbaye de Clairvaux, Lay brothers' refectory
(Photo Courtesy of Troyes la Champagne Tourisme)

This particular manuscript has been chosen because, as determined by Mary and Richard Rouse (Preachers, florilegia, and sermons: Studies on the "Manipulus florum" of Thomas of Ireland, Toronto, 1979, pp.139-45), it was extensively used as an intermediate source by Thomas of Ireland in compiling his very influential florilegium Manipulus florum (1306), which I have edited for The Electronic Manipulus florum Project. An example of Thomas' reception of Liber exceptionum is provided in the fons/fontes apparatus file for the entry Relinquere b in Manipulus florum, which shows that textual variants from the original source were due to the agency of Guillaume de Montaigu or his source manuscript.

A sample of the intended resource was developed in Summer 2026 prior to the submission of an application for major external funding. This sample provides a portion of the quotations attributed to Augustine, Gregory and Jerome.

Index page for the edition-in-progress

An important early result of the seed grant project occurs in the fifth quotation attributed to the first book of Jerome's commentary on Isaiah, which includes both a genuine line from that text and another line (indicated by red font) that has not been found in any digitized Latin text:

Omnes diligunt munera. amicicie gracia post iungende sunt quam amore pecunie. quia nec est uera que redimi potest nec os considerant amicorum sed manus. et eos sancta iudicant quorum exhauriunt marsupium. (fol. 76vb)

It seems likely that the line "amicicie...potest" was a marginal commentary that was mistaken as a correction in Montaigu's source manuscript at Clairvaux or in the textual tradition leading to it. While this particular anomaly was not transmitted to the Manipulus florum, it suggests that more anomalies of this kind may exist in Liber exceptionum that were perpetuated in Thomas of Ireland's florilegium and were thus disseminated in other Latin texts.


©2025-26 Chris L. Nighman
History Department, Wilfrid Laurier University
Centre for Medieval Studies, University of Toronto


Initial seed funding for this project was awarded in February 2026 by the Office of Research Services at Wilfrid Laurier University in the form of an Explore Grant funded by the Social Sciences and Humanities Research Council of Canada.

That seed grant was used to pay the salaries of John Loudfoot (U. Waterloo), Sam Louwagie (WLU) and Ethan Gowland (WLU), who worked as Research Assistants in Summer 2026 to help prepare a sample of the proposed edition.