Five people lean on a parapet at Pena, in Sintra, looking out over the forest toward the coast. Nobody faces the camera. You see the backs of heads, a shoulder, the angle of a jaw, and past them the whole Atlantic plain going hazy in the light. If that composition feels familiar before you can say why, it should. It is one of the oldest tricks in European landscape painting, and the poster trade ran on it for a hundred years.