The Corpus Coelestinianum is dedicated to the publication of texts of all kinds relating to Pope Celestine v (Pietro del Morrone), remembered today as the only pope prior to Benedict xvi who is known to have abdicated. He did so because he felt unequal to the heavy burden of the papal office. This volume aims to edit all the extant letters of Celestine. If one excludes the deperdita and forgeries listed in appendix i, there are 143 texts, consisting of 142 letters and one privilege. One item (no. 70) is anomalous since it takes the form of litterae solemnes (with the address replaced by the words ‘Ad perpetuam rei memoriam’) but has the full dating clause of a privilege. Appendix i lists deperdita and forgeries; to these should be added the letter of 13 September 1294 mentioned in the introduction (p. 51), which was destroyed in the Second World War. The lengthy introduction, which analyses the contents of the letters in detail, emphasises the pope's spiritual and religious goals and his desire for peace among Christian rulers in order to facilitate a crusade.

The number of texts is not unimpressive if one considers the brevity of Celestine's pontificate (5 July–13 December 1294), the lack of a register of his letters and the fact that his successor Boniface viii immediately annulled many of his acts (see below). None the less, inevitably in a work which seeks to gather sources from many different archives and libraries, the haul is not complete: Peter Linehan's Portugalia Pontificia: materials for the history of Portugal and the papacy, 1198–1417 (Lisbon 2013) published three letters omitted in the present volume, one of which survives in duplicate (vol. i. 541–3, nos 869, 871, 872). If one takes into account these additional items, there are eighty-four original letters (ninety-four including duplicates). Ten of these are endorsed with a registration mark, indicating that a register of Celestine's letters once existed. In their descriptions of the originals, the editors record both the registration mark and the scribal signature, if present, but not other chancery marks, which may include the name of the proctor. For this reason, it is worth drawing attention to the entries for nos 20, 53 and 76 in Jane E. Sayers, Original papal documents in England and Wales from the accession of Pope Innocent III to the death of Pope Benedict XI (1198–1304) (Oxford 1999), 442–3, and the entry for one of the exemplars of no. 68 in Wolfgang Hilger, Verzeichnis der Originale spätmittelalterlicher Papsturkunden in Österreich, 1198–1304 (Vienna 1991), 343–4.

The editors, in common with earlier commentators, point out that Celestine's letters, and especially the originals, show that his chancery was functioning properly. In particular, they have found no evidence for Ptolemy of Lucca's claim that Celestine issued sealed blank parchments for their recipients to fill in at will (pp. 57–8). Yet the letters published here are indicative of serious irregularities in Celestine's chancery. Many letters in favour of religious houses, especially those belonging to the eremitical congregation that Celestine himself had founded (later called the Celestinians), were issued not, as would normally have been the case, at the request of the beneficiaries and at their expense, but on the initiative of the pope. This is shown by annotations accompanying the scribal signature; for instance, ‘de curia’, ‘Gratis pro domino papa’, ‘Pro ordine pape’. These letters tend to contain extremely generous favours to their beneficiaries. Other letters reflect Celestine's close alliance with (or, as some historians would say, his subservience to) Charles ii, king of Naples. Celestine appointed Charles's prothonotary Bartholomew of Capua as a notary in his own chancery, and Bartholomew is thought to have exerted great influence over the pope. Celestine's harsh letter, Peccasti, addressed to James (ii) of Aragon, ruler of Sicily and enemy of Charles ii (no. 55), may be the result of this notary's drafting.

Boniface viii's Olim Celestinus of 8 April 1295 (but intended to take effect from 27 December 1294) noted that the former pope ‘fecit diversa et concessit varia minus digne, inordinata et insolita, … sub cuius bulla nonnulla, ut fertur, preter ipsius conscientiam transierunt’. The suggestion that some acts of Celestine emanated from the chancery without the pope's knowledge or approval is not in itself remarkable, for this was a long-standing problem facing the papacy as the quantity of business expanded. However, it may have been especially acute under the unworldly Celestine, who was inexperienced in curial procedures. Boniface's reaction to the situation that he inherited was radical. He annulled completely certain categories of Celestine's letters, which he listed at length. In the final section of the constitution, he suspended the remainder and required that they should be submitted within a certain timeframe to the apostolic see for scrutiny. It is therefore not quite accurate to state, as the editors do, that Boniface suspended all Celestine's acts (pp. 52–3, but cf. pp. 113–14). In their quotation from the constitution (p. 52), they omit the crucial words ‘Ceterum ut sedes ipsa sepedicti antecessoris actus reliquos lucidius possit discutere et in melius reformare ejusque errata corrigere, omissa supplere ac in irritum revocanda deducere’ (my italics).

One of the most celebrated of Celestine's letters is the plenary indulgence for those who visited the church of S. Maria di Collemaggio on the feast of the decollatio of St John the Baptist (no. 64). Such an indulgence was unprecedented, if one disregards the Porziuncula indulgence for which there is no documentary evidence. Boniface, who evidently regarded it as out of proportion to earlier papal indulgences, annulled it in a separate enactment, requiring the prior and brothers of Collemaggio to surrender it along with any other letters of Celestine. The paradox that it was precisely Boniface who greatly expanded the scope of the plenary indulgence for the Jubilee of 1300 is not lost on the editors (pp. 114–16). Boniface's decision in the case of Collemaggio contrasts with his treatment of Celestine's numerous letters in favour of the principal Celestinian house, the abbey of S. Spirito near Sulmona, which he wished to inspect, in order to decide which ones should be quashed and which confirmed (p. 53).

This is a carefully edited and elegantly produced volume. The extensive annotation concerning the letters and the citation of the relevant secondary literature, much of it published locally, are especially welcome.