There is a secret hidden in this painting — can you find it? A shadowy male onlooker in a top hat stands in for us, the viewers. His presence makes us feel like voyeurs, as if we are peeking through a keyhole at these dancers, in the wings of the Paris Opera before the curtains open. The surface of the picture is built up with several thick layers of oil paint. Looking at it, you can imagine the artist working tirelessly with brushes and his fingers to get the textures just right.