What is Emily’s relationship with the Velázquez painting in the play, Disgraced?

Emily was moved to this painting after an incident in which a waiter looked at Amir and Emily and saw something he thought he understood, but could not have understood without knowing them. Emily imagines that the audience who saw Velázquez’ painting must have thought they knew what they were seeing, when in fact there was much more going on in it, in the painter’s life and in Juan de Pareja’s.