Mystery of the Mona Lisa’s smile solved: Second painting shows how da Vinci created an optical illusion to trick viewers

The Mona Lisa’s mysterious expression may have captivated the world, but hers isn’t the only enigmatic smile Leonardo da Vinci created. Researchers examining an earlier painting by the Renaissance master claim to have unravelled the painter’s secret to creating an ‘uncatchable smile’. The study reveals how La Bella Principessa, painted by da Vinci before he completed the Mona Lisa in the late 15th Century, uses a clever trick to lure in the viewer.