One of only three known copies of an important work by Peter the Venerable and from the celebrated library of Parc Abbey.
 
i (paper) + 69 + i (paper) leaves on paper and vellum, unfoliated [collation: i12, ii12, iii12, iv12, v12, vi8+1], each quire with a vellum bifolium in the center, watermark of unicorn similar to Briquet 10015 and 10016 (with dated specimens of c. 1440–1450), with catchwords, ruled in brown ink in single column of forty-two lines (justification: 198 mm × 138 mm, with contemporary notes and marginal additions, written in a textualis libraria script with a half-leaf inserted between folios 7–8 written in an early modern cursive hand, rubrics and headers in red, capitals of two and three lines in alternating red and blue ink, 2 DECORATED INITIALS of six and seven lines, with internal penwork tracery and extended vertical bar border of purple filigree flourishing with spirals and tendrils. Rebound in 2023 in a limp vellum binding formed from reused leaves of a medieval liturgical manuscript, the cover constructed from folded parchment fragments, sewn on three raised supports, with thongs laced through the vellum cover, internal flaps turned in at edges; housed in a custom linen clamshell box with red morocco label and gilt lettering. In excellent condition with only minor cockling and yellowing to vellum leaves, paper extremely clean and crisp, and with ample margins. Dimensions 284 mm × 217 mm
 
Provenance
(1)Parc Abbey, a Premonstratensian house at Heverlee, just south of Leuven. The manuscript was either produced within its scriptorium, as suggested by Mildred Budny, or acquired from one of several secular workshops known to have supplied manuscripts to the community. Until 2023, it was bound together with a second treatise attributed to pseudo-Albertus Magnus (Hugh of Ripelin), the Compendium Theologicae Veritatis, in a characteristic eighteenth-century Parc Abbey binding: brown calf over boards, with a gold-tooled spine title, the abbey’s gilt arms centered on both covers, and the library pressmark on the front endpaper. A seventeenth-century note, possibly a clipped catalogue entry, bound between ff. 7–8 summarizes the principal contents of the treatise and appears to correspond to a seventeenth-century catalogue of the abbey library, which records the work individually. The abbey library was looted in 1796 during the upheavals following the French Revolutionary Wars and was subsequently dispersed by sale in 1829 (see Coppins 2010).

(2) The two texts were offered as a bound unit by Bernard Quaritch Ltd in Manuscripts and Early Printed Books, Catalogue 735 (1956), as lots 15A (Peter the Venerable) and 15B (pseudo-Albertus Magnus).
 
(3) Giles Constable (1929-2021), Cambridge, Massachusetts, Professor of Medieval History, Harvard University, Director of Dumbarton Oaks, author of numerous significant publications and a “giant in the field of medieval history.”
 
Text
The present manuscript preserving the complete text of Contra Petrobrusianos hereticos is one of only three surviving complete copies of the work, which was written around 1140 by Peter the Venerable (c. 1092–1156) (see Fearns 1968, xi–xii). A leading intellectual of his day and abbot of Cluny, Peter was a vigorous defender of orthodox doctrine, and this treatise constitutes his principal response to the teachings of Peter of Bruys and his followers, known as the Petrobrusians. Little is known of Peter of Bruys himself, a reform-minded priest active in southeastern France whose views challenged the sacramental authority of the Church, including the rejection of infant baptism, the doctrine of transubstantiation, and prayers for the dead. He was killed by a mob around 1131, allegedly for using crucifixes to barbecue meat. Following his death, his teachings continued to spread throughout southern France, prompting Peter the Venerable’s response alongside broader efforts at suppression. While polemical in intent, the treatise is invaluable for preserving these dissident beliefs and serves as an important witness to the complex and often spiritually contested landscape of medieval religious life.
 
Contra Petrobrusianos continued to circulate as a doctrinal work long after the disappearance of the Petrobrusians, and it is within this context that the present manuscript was commissioned by Parc Abbey some three centuries later. Founded in the twelfth century, this Premonstratensian house emerged as one of the principal intellectual centers of the Low Countries in the later Middle Ages, maintaining close ties with the University of Leuven and developing a distinguished library rich in theological, liturgical, and scholastic texts. Surviving codices attest to a mixed manuscript economy with an active scriptorium persisting into the middle of the century as evidenced, for example, by a 1456 copy of David of Augsburg’s De exterioris et interioris hominis scribed by Johannes Christus (Heverlee, Archief van de Abdij van Park, ID3.20). The abbey, like many contemporary houses, also relied on commissions from external sources, including nearby convents and secular workshops in the Leuven region (Balberghe 1992). As Mildred Budny (2016) has suggested, the manuscript’s restrained decoration and formal script bear comparison with volumes produced internally in Parc scriptorium, though such an attribution remains tentative. The manuscript’s most distinctive feature is its composite binding, which nests a vellum bifolium deliberately at the center of each paper quire. The rationale for this unusual construction remains uncertain, but the visual effect is striking and lends the volume a notable sense of order and refinement.
 
LITERATURE
Published: C. U. Faye and W. H. Bond, Supplement to the Census of Medieval and Renaissance Manuscripts in the United States and Canada, New York, 1962, p. 284, no. 3; James Fearns, “Introduction,” in Petri Venerabilis, Contra Petrobrusianos Hereticos, ed. James Fearns, Turnhout, 1968, pp. xi–xii (as Manuscript ‘C’ for that text) and page xiv; Mildred Budny, “Double Act: Manuscripts Combining Paper and Parchment,” Presented at the 51st International Congress on Medieval Studies, Kalamazoo (MI), 2016; Related literature: Emile van Balberghe, Les Manuscrits Médiévaux de L’abbaye de Parc: Recueil d’Articles, Brussels, 1992; Christian Coppens, “The Incunabula of Parc Abbey (Heverlee, Leuven),” De Gulden Passer 88 (2010), pp. 23–78.
 
We thank Senior Consultant Sandra Hindman and Peter Bovenmyer for their assistance in preparing this sale.