L'Immacolata Concezione di Aranjuez

17th-century Spain was gripped by the Immaculate Conception like almost no other belief, the idea that Mary alone was conceived free of original sin. Cities held festivals for it, and painters were asked for the image again and again. Murillo returned to it so often that the Prado alone holds five of his versions. This one, from the last years of his life, is among the most weightless. Mary stands on a crescent moon in a rush of cloud and small angels, her body stretched tall so she seems to lift off the canvas. It takes its name from the royal palace at Aranjuez, where it hung in a private chapel before reaching the Prado in 1819.