The subjects in this painting are his two sons Raphaelle and Titian (youngest), named after two of his favorite painters. His third son was Rubens. This painting was done in the trompel'oeil fashion. The bottom step is real and the picture frame looks like the frame of the door they are walking through. Peale painted this to put in his new museum for art and Science, the nations first museum. A ticket to that museum is found on the second step in this painting.  The story goes that when George Washington came to see the museum, he was fooled by the painting and bowed to the boys in greeting. Peale also founded the first art school in US, The Pennsylvania Academy. 
See the original: https://bit.ly/2IBQtx8