This ocatagonal casket, formed of plaques of carved bone and 'alla certosina' marquetry of coloured woods, is made by the Workshop of the Embriachi, in about 1390-1410 in North Italy, Florence or Venice.
The sides are decorated with eight panels illustrating the story of Jason; the lid with a similar number representing the Virtues.

The Embriachi workshop was a famous ivory-carving family who originated in Florence but had a workshop in Venice by the 1430s. They were able to employ local workers specialising in 'certosina' (inlay of stained woods, bone and horn), and the workshop produced items carved in bone (usually horse or ox) with wood and bone marquetry.
Apart from altarpieces the workshop made caskets as bridal gifts to hold jewels or documents, and these were often decorated with scenes from mythology.

The story of Jason was first written in the 200s BC by the Alexandrian poet Apollonius of Rhodes. According to the Argonautica written by Apollonius, Jason led the Argonauts on their voyage to capture the Golden Fleece from Aeetes, King of Colchis on the Black Sea. The King's daughter Medea fell in love with Jason, and by her skill in magic helped him overcome various mortal dangers and win the fleece, which hung from the branch of a tree guarded by a dragon. Having won the fleece Jason and Medea fled from the wrath of Aeetes back to Greece. Jason later abandoned Medea and married a Greek woman causing Medea to seek revenge.