In later copies of Songs of Innocence and Experience, the last three poems are TO TIRZA, THE SCHOOL BOY, and THE VOICE OF THE ANCIENT BARD. In his The Illuminated Blake, Erdman postulates that, this "arrangement of the concluding plates impl[ies] an apocalyptic metamorphosis at the end of the series of emblems, beyond Innocence and Experience." Erdman suggests "that the Eternal Man 'has risen' out of the realm of' 'Contrary States.'
TO TIRZA picture
TO TIRZA text
So looking at these three poems as a group, we ask why they are chosen to conclude Songs of Innocence and Experience. TO TIRZA represents the realization that mortal life has been a temporary substitute for the real thing in Eternity. The mortal body is to be raised a spiritual body. The picture recalls to my mind both the Good Samaritan and the Raising of Lazarus, two stories of healing and recovery.
SCHOOL BOY text
SCHOOL BOY picture
The School Boy strikes me as autobiographical. Young William was not forced to attend school, and his imagination benefited from the freedom he was allowed. He asks how can the adult have the resources to go beyond innocence and experience if the imagination has not been fed and nourished on the sights and sounds and simple joys of unfettered thought and play. He illustrates this by a delightful group of children playing marbles, stretching, climbing, swinging and reading. This plate was originally in Songs of Innocence; now we see it illustrating the stage beyond Experience where the contraries have been resolved through recognition, love and forgiveness. Blake himself has survived the 'blasts of winter' mentioned in the plate, and made us better for it.
The Ancient Bard completes the series on an ambivalent note. The old man is singing and playing his song, and gathers a new generation about him, but he wears a shackle on his ankle. The faces of the children reveal anxiety as they are invited to the new morn and warned about past mistakes. Only if they can avoid being led by those who are not qualified, can they avoid repeating the cycle of despair which the previous generation followed. Blake's unstated answer to the children is that they should trust their own imaginations to provide them with the thread that connects them to the infinite.
So perhaps as a group the three poems are meant to be an invitation to go beyond Experience into Blake's favorite place, the world of Imagination and Vision.