The two remaining figures examine the central structure and ponder what they see.  
The artist's first version of this work is alternately known as the Chatsworth version and more closely resembles a Guercino work painted a decade earlier.  The figure on the right affects a statuesque pose and is dressed in a gold cloth up top and a blue cloth at bottom.  The only other figure looking at her is leaning over to her immediate left and he is dressed in a red cloth and white sandals and holds a staff in his right hand.  The two remaining figures examine the central structure and ponder what they see.  Originally titled Happiness Pursued by Death on its 1640 completion, its current title has no known source in the classics.  FTP, identify this painting that depicts four shepherds at a tomb in the titular region in southern Greece, a painting by Nicolas Poussin whose Latin title can be translated as "I too was once in Arcadia."
The artist's first version of this work is alternately known as the Chatsworth version and more closely resembles a Guercino work painted a decade earlier.  
Et in Arcadia Ego (accept early answer of Happiness Pursued by Death; prompt on any English variations of "I too was once in Arcadia" or "I, Death, was in Arcadia too" as there's no exact accepted translation to English)