Giorgio Schiavone, 'Saint Peter Martyr', probably 1456-61

A saint holding a lily and a book gazes upwards, seemingly untroubled by the curved knife which splits his skull and the dagger in his shoulder. His hair is tonsured, or shaved, to show that he was a member of a religious order, and he wears the black and white uniform of the Dominicans. This is Peter Martyr, the second Dominican saint and their first martyr.

The figure once formed part of the right lower tier of a large polyptych (multi-panelled altarpiece) painted between about 1456 and 1461 by Giorgio Schiavone for the funerary chapel of the wealthy Roberti family in the church of San Nicolò in Padua. Saint Peter Martyr’s panel must have been placed on the right side of the altarpiece alongside Saint John the Baptist: they both look up in the same direction, towards where The Pietà would have appeared.

Peter was born in Verona in 1206 to parents who were heretics – Christians who disagreed with the doctrine of the Catholic Church. He joined the Dominican Order in the 1220s and became one of its most fervent preachers. In 1251 the Pope made him head of the Inquisition for Milan and Como, an office he carried out with such enthusiasm that the heretics of northern Italy hired two assassins to kill him.

On 6 April 1251 Peter was walking from Como to Milan when he met one of these assassins, Carino da Balsamo, outside a wood. Carino struck Peter on the head with his falcastro (a curving dagger with a long handle, like the one in the painting). Peter clung on to life, reciting the Creed – an early statement of Christian faith still widely used in Christian liturgy – and is said to have written its opening words in his own blood, as shown in The Assassination of Saint Peter Martyr by Giovanni Bellini. To kill him, Carino stabbed Peter through the heart with a dagger. Peter’s body was carried to Milan; miracles ensued and he was swiftly declared a saint. Carino, his murderer, repented and became a friar himself.

The lily is the symbol of Peter’s lifelong chastity, while the book represents his writings and his scholarly attitude to his faith. The Dominicans believed in intellectual rigour and the pursuit of truth. Dominican friars took religious vows but were not confined to a monastery. They lived in towns and cities, as the Order had been founded to provide educated preachers and teachers for a growing urban population. The Dominicans were especially important in fifteenth-century Padua as they were closely involved in its university, one of the oldest in Italy.

Peter’s robes stand out against the burnished gold background which has been regilded. His bare toes peep out from under the folds of his robes, and one juts out over the edge of the marble parapet – this links the sacred space in which the saint stands with the earthly space of the Christian viewers. He is painted in a very similar way to Saint Peter Martyr by Carlo Crivelli – you can see pulsing veins in the foreheads of both figures.