File:Medieval papal bull of John XXIII (plan and reverse). (FindID 525676).jpg

English: A Medieval lead Papal bulla: The obverse (recta) depicts the faces of St Peter and St Paul and usally below there is the inscription SPASPE (SPA = Sanctus Paulus, SPE = Sanctus Petrus), but this is unclear, all of which are surrounded by a beaded border, flanking the outside edge of the bulla. St. Paul is seen on the left looking right, with a long pointed beard, and St. Peter is on the right facing left, with a rounded face and beard and hair formed from pellets. This surface is damaged and has grooves which did not occur recently with the exception of one notch at the edge. The reverse (verso) bears the legend IOhAN/ N[VS PP] / XXIII , within a beaded border. Again this surface is damaged, but not recently. The surface of the bulla has a grey/white coloured matte patina. It measures 38.63mm in diameter, 5.74mm in thickness, and weighs 51.1g.

The reverse legend suggests that this is a bulla of Pope John the 23^rd. However, Pope John the 23rd was a twentieth century pope (1958-1963) and this is clearly a medieval bulla. Instead, this seal seems to refer to Baldassarre Cossa (c. 1370 - 22 December 1419), who was antipope John XXIII during the Western Schism. The Western Schism is the period (1378-1417) in the Western church when two (and then three) popes simultaneously claimed to be legitimate. Antipope John XXIII was pope between 1410 and 1415. He was one of the seven cardinals who, in May 1408, deserted Pope Gregory XII, and, with those belonging to the obedience of Antipope Benedict XIII, convened the Council of Pisa, of which Cossa became the leader. They elected Pope Alexander V in 1409. Cossa succeeded him a year later. This is the fourth example of a bulla of Antipope John XXIII to be recorded on the PAS database; SWYOR-F52016 from North Yorkshire, NCL-47CBF6 from Lincolnshire, and SF6390 from Suffolk.

There are large numbers of bullae known from the time of some Avignon Popes (as the Unofficial Popes are now known), who seemed to have issued more documents than the normal Popes, but few are known of John XXIII. Another example is held by the British Library: W de G Birch 1900, Catalogue of Seals in the Dept of Manuscripts in the British Museum [now B. Library] vol. 6, BM, London, 290-1 no 21, 919. The rarity of this pope would actually fit in with the general paucity of bullae in the 15th Century.

Papal bullae were used as seals on official papal documents sent out from Rome (during the schism, Avignon) as a means of authentication. Tim Pestell has stated on other PAS bulla records: "Papal bulls came as two basic types, according to the contents of the document: Tituli, or "Letters of Grace", essentially granted or confirmed rights, conferred benefices or promulgated statutes. They generally had their lead bullae attached with cords of silk. Mandamenta, or "Letters of Justice" were mandates that conveyed papal orders, prohibitions or injunctions, and had their bullae attached by hemp threads". They may have also had a secondary use as an amulet.

The above information was copied from the SWYOR-F52016 record which Tim Pestell and Geoff Egan contributed to.