A painting by the Flemish Baroque master Peter Paul Rubens, thought lost for more than four centuries, has been discovered in a Paris mansion, an auction house has revealed. Osenat, based in Fontainebleau, announced on Wednesday that the work Christ on the Cross, painted in 1613, was identified during an inventory carried out in late 2024. Jean-Pierre Osenat, president of the auction house called it the "defining find" of his career. It will go under the hammer on 30 November. Rubens (1577-1640) is regarded as the leading figure of the Flemish Baroque tradition. The canvas shows Christ crucified, "isolated, luminous, and standing out vividly against a dark and threatening sky". Behind Golgotha, Jerusalem appears "illuminated but under stormy skies". The auction house said the piece is in very good condition and has been authenticated after extensive research by Nils Büttner, chair of the Centrum Rubenianum in Antwerp and an expert on Rubens. Although Rubens produced many religious commissions for churches, the 105.5cm by 72.5cm oil painting was most likely created for a private collector. The work later belonged to the 19th-century French academic painter William Bouguereau, before passing into the hands of the Parisian family whose mansion housed it for generations.