Dating from the 1450s, this beautifully calm and serene painting by Piero della Francesca (c141020-1492) depicts the baptism of Christ by St John the Baptist. It was painted in the traditional Italian medium of egg tempera; the panel was the central section of a polyptych, a work painted across many panels of wood. It may be one of Piero's earliest extant works. Other parts were painted in the early 1460s, by Matteo di Giovanni (active 1452, died 1495). The altarpiece was in the chapel of Saint John the Baptist in the Camaldolese abbey (now cathedral) of Piero's native town, Borgo Sansepolcro.
According to the Gospels, John was about six months older than Jesus and their mothers were cousins. He had gone to live in the desert as a young man, surviving on locusts and wild honey and wearing animal skins. He re-emerged some time later preaching the need to repent and be baptised in order to prepare for the coming of the Messiah.
The painting shows the key event in John's life, when Jesus comes to him asking for baptism and John pours water over his head. To the left of Christ stand three angels while in the background another figure undresses ready to be baptised. In the far background walk some robed figures with elaborate headwear. The dove symbolises the Holy Spirit. It is foreshortened to form a shape like the clouds. God the Father, the third member of the Trinity, may originally have been represented in a roundel above this panel.
Piero uses cool, flat colours and simplified forms to generate a sense of spiritual peace, which is amplified by a careful geometric composition. The artist has placed the figure of Christ at the centre of the picture. A series of strong vertical lines runs through the composition. The main one runs from the point of the arch down through the beak of the dove, through the trickle of water, down the middle of Christ's face, between his clasped hands and ends at the heel of his right foot. Other vertical lines are formed by the tree trunk, the central angel figure on the right, the figure of the Baptist himself and the figures and their reflections in the background.
Strong horizontal lines run through the wings of the dove and clouds and the tops of the heads of Christ and St John. The proportions used in the painting are based on what is called the Golden Section. Its exact measurements are extremely complex (see websites such as www.goldennumber.net) but were considered by many in the classical world to have mystical properties. At its simplest, the Golden Section refers to the way in which smaller parts of the painting are proportionate to the larger parts. This mathematical precision of the painting is relieved by the bend in the river, the curves of Christ's loincloth and, most interestingly of all, the distribution of weight in the picture. Although the two main figures would appear to be standing squarely, if you look closely you can see that Christ has all his weight on his right foot as if he was walking forwards and St John seems to be pushing off from his left. All these elements help to bring a sense of visual tension to the painting.
Studying "The Baptism of Christ" - and indeed much of the work of Piero della Francesca - is an ideal way to introduce pupils to the importance of composition in visual art. Understanding how different parts of a composition relate to each other is vital for appreciating how pictures work. Foreshortening and perspective are strong elements in Piero's work.
You could set up figure-drawing sessions to challenge students of different ages and abilities to create the effect of recession. Students could look at the work of Uccello, for instance "The Battle of San Romano" (1450), for further inspiration.
Although the proportions of the Golden Section are complex, it is roughly five eighths to three eighths. Older students could try to explore its use within the painting, vertically by comparing the tree with the overall composition and horizontally through the wings of the dove and clouds with the width of the two panels comprising the picture.
Piero's use of large, simple geometric shapes and his pale, limited palette have led to some seeing him as a father figure of Cubism. Older students could explore this connection further and look for his influence in the work of Cezanne and Picasso.
Original viewers would have recognised the background landscape in which Piero has set his figures: the town, visible in the distance to the left of Christ, may be Borgo Sansepolcro. Pupils could update the painting by replacing the background with that of their own neighbourhood. Discussion could focus on what features or landmarks they might select for their composition. They could make preliminary sketches outside and compositions could be created with a digital camera and computer programs such as Photoshop.
The picture is full of conscious compositional techniques. For instance, it is notably symmetrical. Pupils could explore how symmetry contributes to its overall effect. Again, Piero's characters alternate between full-frontal presentation and profiles. If pupils make a series of drawings to investigate profiles, they could then use a strong light source to create silhouettes to trace around and paint. How does this effect differ from a full-face portrait? Is it stronger?
The National Gallery Companion Guide by Erika Langmuir, National Gallery, pound;9.95
James Sharp is art co-ordinator at Elmhurst Primary School, London borough of Newham