Tomb of Antipope John XXIII

The marble-and-bronze tomb monument of Antipope John XXIII (Baldassare Cossa, c. 1360–1419) was created by Donatello and Michelozzo for the Florence Baptistry adjacent to the Duomo.

[3] The tomb monument's design included figures of the three Virtues in niches, Cossa's family arms, a gilded bronze recumbent effigy laid out above an inscription-bearing sarcophagus supported on corbel brackets, and above it a Madonna and Child in a half-lunette, with a canopy over all.

[5] The tomb monument was the first of several collaborations between Donatello and Michelozzo, and the attribution of its various elements to each of them has been debated by art historians, as have the interpretations of its design and iconography.

Although he expected his departure would disperse the council, the members of which he called to join him under the protection of Duke Frederick IV of Austria, it continued to operate where they were.

[9] Cossa was ransomed by the Republic of Florence in 1419 (Louis III had abandoned the allegiance of Sigismund in 1417), as orchestrated by Giovanni di Bicci de' Medici.

[14] Cossa's body was moved to the Baptistry and the nine-day funeral, as prescribed by the Ordo Romanus, was well-attended by the Florentine elite and the papal court.

[15] Cossa's corpse was crowned with a white mitre with his cardinal's hat at his feet on the funerary bier during the rituals, which took place entirely within the Baptistry and Duomo.

Cossa's last will and testament—written on his death bed on 22 December 1419—made several of the customary Florentine civic bequests, acts of charity, and traditional ecclesiastical courtesies, but the bulk of his estate was left to his nephews Michele and Giovanni.

[22] Valori died on 2 September 1427, by which time Guadagni was also deceased and Uzzano had long lost interest, leaving the remaining work of commissioning entirely to Giovanni, or—more likely—Cosimo de' Medici.

[28] The Calimala's acquiescence is traditionally explained by Cossa's donation of the relic of the right index finger of John the Baptist (and 200 florins for an appropriate reliquary) to the Baptistry.

The long and complicated history of the relic would only have increased the legendary status of the finger: Philotheus Kokkinos, Patriarch of Constantinople presented it in 1363 to Pope Urban V, who passed it to his successors Gregory XI and Urban VI, who was dispossessed of it during the siege of Nocera, after which John XXIII bought it for 800 florins and wore it on his person before hiding it in the monastery of Santa Maria degli Angeli.

[33] On 2 February 1425, Bartolomeo Valori and Cosimo de' Medici requested 400 of the 800 florins that had been deposited with the Calimala, likely for work already completed.

[34] This deposit was insurance in case the executors left the tomb unfinished and the Calimala was forced to pay for its completion, as it had been obliged to with the finger reliquary.

[40] Although the original source for this claim is unknown, it has gained credence with modern scholars as the effigy alone would have cost 500 florins,[41] yet its exactness may be taken with a grain of salt.

[48] The canopy's interaction with the columns and conceit of being supported by the Baptistry cornice make the tomb monument further "wedded to the architecture" around it, even if the marriage is morganatic.

Although the style of the work is thoroughly classicising, the overall form reflects the grandest type of the medieval Italian wall tomb, in which the vertical piling-up of a series of different elements is characteristic.

[50] Italian Gothic sculpture always retained considerable elements of classicism, and it was not necessary for Donatello and Michelozzo to adopt a radically original overall scheme from those of Tino di Camaino (c. 1285–1337), the Siennese sculptor whose wall-tombs of a century before had been very influential throughout Italy.

[54] The base slab, or pylon, of the tomb monument rests on a 38-centimetre (15 in) high plinth, separated by a cornice and concave mouldings.

Such a motif is unprecedented in Tuscan funerary sculpture but found at this date in Venice, Padua,[41] and especially Cossa's native Naples.

[62] Besides underscoring the antiquity of the tomb monument, the main purpose of the tall yet poorly finished Virtues is to put additional vertical distance between the viewer and the effigy, which has the cumulative effect of de-emphasizing the peculiarities of Cossa, in favor of a generic pontiff (i.e. a potential line of Florentine popes), by blunting the "immediacy" of the trope of lying in state, which was otherwise dominant on Quattrocento wall tombs.

As Donatello's Marzocco for the papal apartment in Santa Maria Novella conveyed Florence's ambivalence towards Martin V (as both a source of prestige by visiting, and a potential adversary of the Republic), the lions supporting the bier contextualize the tomb monument's support for John XXIII's claim to the papacy by cementing it as a Florentine claim.

[79] There was no precedent for a three-dimensional gilded-bronze effigy on an Italian tomb monument; there was, however, a 6-foot (1.83 m) gilt bronze statue on the balcony of the Palazzo della Briada in Bologna commissioned by Pope Boniface VIII.

[81] Behind the effigy is a 1.34-metre (4.40 ft) tripartite pylon with sunk molded borders supporting the cornice and framed by two additional Corinthian pilasters.

[82] Above the effigy and Madonna is a gilt-edged architectonic canopy decorated with patterned stemmed flowers, giving the conceit of being supported by the ribbed brass ring, an impossibility given its weight.