Pierre Mignard, 'The Marquise de Seignelay', 1691

In this imposing portrait, Pierre Mignard transforms Catherine-Thérèse de Goyon de Matignon-Thorigny, the Marquise de Seignelay (1662–1699), into the sea-goddess Thetis. A luminous blue robe cascades in folds over her gold-embroidered gown. The generous use of ultramarine – an expensive and high-quality blue pigment – was unusual for the period. It, like the portrait, is a deliberate display of wealth, status and power.

At the Marquise’s side stands a young boy dressed as Achilles, who, according to Greek legend, was the son of Thetis and the mortal Peleus and the greatest warrior of the Trojan War. He wears ornate armour and holds a spear, with a shield and helmet lying at his feet. This is likely Catherine-Thérèse’s eldest son, Marie-Jean Baptiste (1683 – 1712) who was eight years old at the time. This is a striking choice because Achilles is usually depicted as a mature warrior. It has been suggested that the winged Cupid might be her youngest son, Théodore-Alexandre (1690? - 1695?), although this seems unlikely given his nudity.

Catherine-Thérèse was the widow of Jean-Baptiste-Antoine Colbert (1651–1690), the Marquis de Seignelay, who died a year before this portrait was painted. The Marquis had been appointed Secretary of State for the Navy upon the death of his father, Jean-Baptiste Colbert (1619–1685), who held the position before him. Due to their naval profession, the Colbert family had strong ties to the French colonies in the Americas. Both father and son were responsible for drafting the Code Noir (Black Code, 1685), which regulated the commerce and discipline of enslaved people in the French colonial empire.

Although once thought to depict a Mediterranean volcano, perhaps Vesuvius, the background of this portrait has recently been identified as Martinique, an island in the West Indian ocean, which was purchased for the French crown by the Marquise’s father-in-law in 1664. The wealth of the island lay in sugar production. This was exploited by the French who used enslaved labour from the Senegalese coast to work the plantations. As the source of Seignelay family’s wealth and power, Martinique would have been deemed a fitting location for the figures.

The topographical accuracy of the landscape in the background suggests that Mignard worked from contemporary engravings or sketches to complete the scene. The volcano has been identified as Mount Pelée – the French translation of Peleus, Thetis’s husband. Mignard thus inventively alludes to Catherine-Thérèse’s recently deceased husband through the smoking volcano in the distance.

One of the most striking elements of the picture is the elaborate shell cup supported by gold mounts which overflows with pearls and coral, offered up by Cupid to the Marquise. Such cups were prized novelties in sixteenth and seventeenth-century Europe. Its inclusion in the painting speaks to France’s position as a global power and to the Marquis de Seignelay’s naval exploits. More shells are scattered at the water’s edge, originating from across the globe, commemorating her husband’s career in the French royal navy and his famed collection of rare objects. Together with the coral, pearls, and cup, the shells are materials of empire used to celebrate the status of the sitter and the riches gained through trade. The same iconography is used in Mignard’s earlier portrait of Louise de Kéroualle, the Duchess of Portsmouth, painted in 1682 (National Portrait Gallery, London).