Rembrandt couldn’t decide whether to depict a rich man who commissioned a portrait standing up, or on his horse. And when he did determine how to show the wealthy gentleman, on horseback, he painted over the original image of the “sitter” standing up. Both portraits appear when the painting is x-rayed. Was canvas so expensive, or did Rembrandt not want a mere commissioned picture crowding out the personal works in his studio?

Nicolas Poussin admired the art of antiquity, which came down to him (and to us) mostly as sculpture. This may be why Poussin’s The Triumph of Pan seems like a sculptural frieze in paint, an odd paradox of permanence and perpetual movement.