One of the most memorable experiences in my travelling life was to be shown around the Prado Museum in Madrid by a curator of Spanish paintings from the National Gallery. “This,” he said, pointing to a streak of light across the canvas of Velázquez’s great painting Las Meninas, “is my favourite white line in the whole of art history.” He went on to describe the extraordinary visual power of that simple stroke of white lead paint and how it illuminated and unified the image. For the small group of us clustered in the gallery, he brought the painting to ... Read More