PECIA. — As a term of the medieval book trade, it originally denoted the entire hide of a calf or other animal, tanned for writing use (parchment), or the sheet obtained from it by trimming the margins; it later came to denote the gathering formed by folding the entire sheet in four, similar to the modern printed sheet of an in-4° volume, and, by extension, the loose gatherings of a book, whatever the format or number of sheets, even when made of paper. In old manuscript inventories, if the book was not bound, the number of p. composing it is usually indicated.
The p. acquired a particular function in university book production (13th and 14th centuries). To guarantee the fidelity and integrity of the texts required for instruction, the stationarii had to possess, for each text, an exemplar approved and corrected by the professors; this standard text consisted of loose, numbered p., which were lent to copyists one at a time so that, once the work had begun, the same work could be copied simultaneously by many people. Thus the p. became a basic element in the copying of manuscripts, as well as a unit of measurement for the payment of copyists, according to the tariffs established by the universities themselves. Moreover, to provide the commissioner with a further guarantee, the copyist often marked in the margin the beginning or end of each individual p., indicating its sequential number; when such marks are absent, the trained eye recognizes the beginning of the p. from slight variations in handwriting and ink, or from other incidental clues. In this way, the number of p. and their respective beginnings make it easy to identify manuscripts deriving from the same exemplar.
The recent studies of J. Destrez (d. 1950) make it possible to regard observation of the p. as fundamental to the textual criticism of works disseminated through the universities. Among other things, he established that in the major centers (Bologna, Paris, Oxford, Naples) the p. were marked in different ways; only one exemplar at a time circulated in any given place, and it had a different number of p. on each occasion. It is therefore possible to trace the dissemination of a text and establish the date and provenance of individual manuscripts, supplementing strictly paleographical criteria.