This sculpture is one of Donatello's greatest works, and one of his most enigmatic and challenging. The subtlety and shallowness of the carving means the scenes appear almost to have been drawn on the surface of the marble. Viewed from any distance, unlike sculptures carved in higher relief, the images merge into the whiteness of the stone.
We are so used to seeing "traditional" marble sculptures all around us that it can be difficult to recapture the power and impact that works like this once had. The vast distance between the time we live in, and that in which this sculpture was made, means details that were once strikingly innovative can be easily overlooked.
The subject matter is now unfamiliar. In the centre of the composition we see Jesus, surrounded by four winged cherubs, ascending to heaven. His right hand is raised in a gesture of blessing, and with his left he passes the keys to the kingdom of heaven to St Peter. In the space beneath his feet, in the distance, are three trees.
The kneeling figure on our left is his mother, the Virgin Mary. She is depicted older than was usually the case (she was often shown as barely adolescent). Five apostles (the original followers of Christ) are arranged in a row alongside her. In the left-most corner are two embracing angels.
On St Peter's right are a further five apostles shown in remarkably dramatic postures.
Religious subjects were depicted frequently in the Renaissance (the name often applied to the flowering of arts and culture in Italy during the 15th and 16th centuries). In earlier, medieval art it was usual to give saints a symbol that enabled the viewer to identify the figure represented.
Donatello has not used this convention, which makes it difficult for us to identify the individual apostles. In fact, he has combined two separate events from the gospels into one scene.
The giving of the keys, described in St Matthew's gospel, was interpreted as Christ giving the leadership of the Church to St Peter, and the founding of the papacy: "And I say unto thee, That thou art Peter, and upon this rock I will build my church; and the Gates of hell shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven."
The Ascension, which occurred after Christ's death and resurrection, was described by St Luke: "And He led them to Bethany and He lifted up His hands and blessed them. And it came to pass that when He blessed them, He was parted from them and carried up to heaven."
The Ascension is not among the most commonly depicted scenes of Christ's life, perhaps partly because it was so challenging to illustrate. Sometimes artists chose to show only Jesus's feet visible at the top of the picture, almost as though he had taken off like a rocket. Donatello has endeavoured to create a convincingly three-dimensional landscape. Generally, this has been less of a concern for medieval artists, who did not use scientific or linear perspective. Early Renaissance artists often used architectural settings, created with linear perspective, to suggest a real space.
Through careful investigation, students will be able to identify the approaches used by Donatello to create the illusion of real space. For example, he has used several rows of trees to indicate depth. Objects that are further away are reduced in scale, and in most cases carved in shallower relief than those in the foreground. Figures are overlapped, and the parts of some figures nearer to the viewer are in higher relief.
Donatello is often thought of as a quintessentially Renaissance artist.
Secondary students can try to identify which elements of this sculpture reflect classical, medieval or Renaissance conventions of art. For example, figures may initially look similar to those in Roman art, but their emotional expressiveness is characteristic of later medieval Gothic art. In addition, the overall design is based on linear perspective, an innovation of the Renaissance.
Why does the sculpture look this way? Unravel this puzzle with students by encouraging them to look closely at technique and context. The technique is rilievo schiacciato, "squashed" or "flattened relief", and represents another of Donatello's innovations. The artist has skilfully carved away only a little marble before reaching the background. This precise skill was most admired when the relief was made. Ask students why he may have chosen to use this technique on this thin block.
Was the sculpture made for close inspection just above eye-level? If displayed at any great height or distance, it would have been very difficult to read.
We do not know the sculpture's exact date or why it was commissioned. It may have been commissioned for the Brancacci Chapel in the church of the Carmine in Florence. If so, it would have been part of a much larger scheme. We do know that by 1492 the relief was in the collection of the great Medici family, hung in a walnut frame. By this date it was already esteemed as a work of art.
We don't have to look too hard to find examples of relief sculpture all around us in our daily lives. Donatello was not the first artist to use the medium, nor was he the last. Few artists, however, have used adapted relief to depict such a challenging subject so successfully and with such dramatic, beguiling effect.
Stuart Frost is a gallery educator at the Victoria and Albert Museum, London
Donato di Niccolo di Betto Bardi, better known as Donatello, was arguably the greatest sculptor of the 15th century. He was born in Florence, a city frequently described as the birthplace of the Italian Renaissance. He is most famous for his bronze stature of David - the first nude bronze since Antiquity - now in the Museo Nazionale del Bargello, in Florence.