跪着的修女

This looks, at first, like an ordinary piece of piety: a nun bent over her prayer book, lit by a single window. The trick is that Martin van Meytens painted both sides of the panel. Turn it around and the same nun kneels from behind, her habit lifted, with a leering old man watching from a corner. Painted around 1731, it belonged to the Swedish ambassador in Paris, who kept the picture turned to its decent face and showed the other only to chosen guests. Eighteenth-century libertine taste liked exactly this game, letting the painted voyeur carry the guilt so the owner could claim he was only admiring the brushwork. The nun's downcast devotion on the front was always meant to be flipped.