Study of man often featured in works by the Flemish master reveals hidden painting of woman beneath model’s beard

Is it a bald elderly man with a big bushy beard and a wine-addled stare? Or a friendly young woman with flowing locks and a crown of braids?

To Belgian art dealer Klaas Muller, an answer to that question mattered less than the fact that this particular take on the duck-rabbit optical illusion was painted by one Peter Paul Rubens.

Three years ago, the Brussels-based former gallerist managed to effectively acquire not just one but two studies of heads by the Flemish baroque master in one painting, paying the “reasonable price” of less than €100,000 at an online auction.

The auctioneer, which Muller would identify only as a “lesser-known auction house in northern Europe” for fear of encouraging too much future competition, had advertised the work as an undated study on paper by an anonymous master of the “Flemish school”.