This altarpiece is the earliest known example to show the baptism of Christ as the central image; the Virgin and Child usually took this position in large multi-panelled altarpieces.

It was made for a chapel dedicated to the feast commemorating Saint John the Baptist’s death, in the infirmary of Santa Maria degli Angeli, the Camaldolese monastery in Florence. One of the monastery’s monks, Don Filippo Nerone Stoldi, commissioned it in memory of his mother, Monna Agnola (Angela), and his deceased relatives. The church contained several similar altarpieces which were privately commissioned, often by families of the monastery’s monks, which served as memorials. We know from the monastery’s records that one of the monks’ duties was to say prayers for the souls of the dead on days specified by the families.

Surviving documents reveal that the chapel was founded according to Angela’s wishes. She left money in her will for the foundation of the chapel and all its furnishings; the will also instructed that Mass should be said for her and her husband on 20 April as well as the feast day of the martyrdom of John the Baptist (29 August).

Although the chapel was dedicated to the saint’s martyrdom – he was killed on the orders of King Herod – the central panel depicts the key moment in his life: when he baptised Christ in the river Jordan. The gory moment of his decapitation was reserved for a small panel in the predella. We don’t know exactly why Angela chose Saint John the Baptist for her chapel. Perhaps her son was called Giovanni but changed his name to Filippo after becoming a monk or, more likely, because John the Baptist was the patron saint of Florence. There were two other chapels in the church that were dedicated to him.

The altarpiece was moved in the fifteenth century to the church of San Giovanni Decollato (literally meaning ‘Saint John decapitated’) in the town of Sasso, near Arezzo. The church had become a Camaldolese institution in 1414 when it was united with Santa Maria degli Angeli. The subject matter made it the ideal altarpiece to use as the church’s high altar.

It was probably originally much larger. The predella is missing a central scene and there might have been two more saints on the main tier– possibly Saint Michael the Archangel, in honour of Angela, and Saint Philip, in honour of her son.

At some point before it entered the National Gallery the uppermost panels that sat on top of the main tier were replaced with three small panels by Giovanni di Milano showing the Virgin Mary, Saint John the Baptist and the Apocalyptic Christ (Christ as the judge of mankind). These panels belonged to a different altarpiece altogether and they have now been removed and are displayed separately. Three panels by Niccolò di Pietro Gerini – including an image of the blessing Redeemer (Christ seated on the clouds), now in the Alte Pinakothek, Munich – have been identified as the original pictures that crowned the altarpiece.