It’s the defining artwork of the Catholic Church (according to George Clooney’s character in the 2014 movie The Monuments Men) and as great a work of art as any ever stowed in a salt mine for safekeeping. It is endlessly scrutinized and never wholly comprehended. It’s a cabinet of curiosities, both for the ingenuity of its construction—a set of painted panels unfolding to reveal another set within—and for the way it embodies the career of the enigmatic artist who made it. It is the Adoration of the Mystic Lamb, completed in Ghent in 1432, and the focus of a new show there, “Van Eyck: An Optical Revolution.”

Vasari called Jan van Eyck, who is thought to have lived from 1390 to 1441, “the inventor of oil painting.” Scholars have since softened that assertion, and a different Van Eyck has emerged: a painter who struck a sublime balance between the claims of divine light and natural light, between iconographic patterns and sensual renderings of the way things look and feel.