Donatello’s bronze statue Saint John the Baptist (1457) decorates the chapel dedicated to the Saint at the Siena Cathedral. In his lifetime Donatello was held in high esteem, being sought after in places outside of his native Florence, like Venice, Padua, Pisa, and Naples. In particular, the artist cultivated a special relationship with the neighboring republic of Siena, and in 1457 he declared his wish to spend the rest of his life there. Around that time, the bronze statue of Saint John the Baptist was brought to Siena, and ten years later, it was listed in the inventory of the Siena Cathedral. At its delivery, it was noted that the statue was missing its right forearm. Scholars tried to explain it in several ways. One possibility is that the sculpture was sent over to Siena in sections, to prevent damage and to manage import costs. However, local sources from the 16th century claimed that Donatello left the statue incomplete because he was never paid in full. This claim was repeated by Vasari in Lives of the Most Excellent Painters, Sculptors, and Architects published in 1568. Thus, it is possible that Donatello never actually completed the statue and that the right arm is an addition executed by an unknown artist.

Almost two decades earlier, Donatello created another sculpture of Saint John the Baptist (1438): the citizens of Florence commissioned the wooden figure for the chapel of the Florentine community in the Santa Maria Gloriosa dei Frari in Venice. In both cases, Donatello positioned the figures similarly, standing with their legs spread, their mouths open as if preaching a sermon, and a raised arm. But significant differences are evident in style and appearance. It is possible that Donatello wanted to create something unique for his Sienese clientele, to avoid comparisons to the sculpture in Frari. In the Sienese version, Donatello depicts an older man of bigger proportions, more athletic and more muscular. In contrast to the Frari figure, the statue in Siena is executed more expressively: the lines of the silhouette are no longer smooth; they are broken and jagged.

Another reason for the stylistic shift could have been that Donatello wanted to accommodate the statue to Sienese taste. Two sculptures by Sienese artists, Saint John the Baptist (ca. 1418-1423) by Domenico di Niccolo dei Cori and Saint John the Baptist (ca. 1417) by Sienese sculptor Jacopo della Quercia, share commonalities with Donatello’s statue. The Sienese artists show a prototype of Saint John that differs from Donatello’s figure in Frari, in which Saint John is presented as a hermetic saint weakened from his ascetic practices. The statues of Cori and Quercia have the same wiry and sturdy qualities found in Donatello’s bronze sculpture. This Sienese model shows a more animated and assertive type of Saint John the Baptist. Whether or not these artists influenced Donatello, the bronze figure of Saint John the Baptist is indicative of Donatello’s later style. In this period, his figures were more expressive and harnessed greater emotional intensity. Other examples of his later style include the bronze Judith and Holofernes (1457-1464) and the wooden Magdalene Penitent (1453-1455).