Paul Bril, 'Diana and Callisto', probably 1620s

In Book II of the Metamorphoses, a poem by the Roman writer Ovid, Callisto was one of the virginal companions of Diana. She was raped by Jupiter, ruler of the gods, and became pregnant.

One day, while out hunting, Diana and her companions decided to bathe in a stream. Callisto was forced to undress – her pregnancy was revealed and Diana expelled her from the group. She gave birth to a son, Arcas, and was transformed into a bear by Jupiter’s jealous wife, Juno. Years later, her grown-up son was out hunting when he came upon his mother, still in the form of a bear. Not knowing who she was, Arcas was about to kill her when Jupiter changed them into constellations, the Great Bear and Little Bear.

in this painting, Diana, already largely undressed, is seated on a rock in the lower right corner, surrounded by her attendants. A bow, two quivers of arrows and items of clothing lie on the ground beside her. She is gesturing to the group on the other side of the stream, where several nymphs are forcing Callisto to take off her clothes. Other nymphs with bows and spears stand watching, or are already naked and ready to enter the water.

The discovery of Callisto’s pregnancy was a favourite subject with European patrons and artists from the fifteenth century onwards, perhaps for the opportunity it gave to show a number of nude female figures. It was painted on a grand scale by both Titian (Diana and Callisto) and Rubens.

Paul Bril was born and trained in Antwerp and the roots of his style were deeply Flemish, harking back to Pieter Bruegel the Elder and Joachim Patinir. After moving to Rome in 1575 he came into contact with the work of Italian artists, in particular Annibale Carracci and his followers; the encounter modified his style profoundly, which became calmer and more classicising.

In the early 1620s Bril collaborated with Domenichino, Guercino and Giambattista Viola on the frescoes in the Stanza dei Paesi in the Villa Ludovisi. Under the influence of the Bolognese school he also produced a number of landscapes in which broad tranquil settings are inhabited by mythological figures, usually, as here, placed in the lower foreground.