The Piper's Joy and the Bard's Sorrow

The "Introduction" of Songs of Innocence begins with two quatrains wherein a child exhorts a piper to play songs about a lamb, the very symbol of innocence. These songs touch the child to tears of ecstasy. The poem goes on to tell the reader that after a repetition of this startling performance the piper sits and records all of his apparently thrilling children's songs, which serves to advise the reader that they will continue to delight other children.
In the "Introduction" to Songs of Experience, the genial piper has become an omniscient bard, a professional poet. This bard is either issuing or witnessing a call for the earth to change its most basic patterns of dark and day. While the exact line of who is calling to whom is murky, the tone of jaded weariness is clear, and a clear departure from the previous tone of mindless enjoyment. In its final sections, the Experience "Introduction" gives the reader and impression of questioning and chaotic earth whose darkness signifies the denial of the light of God's face.
A similar juxtaposition can be seen in the final selections from each section reprinted in the textbook, "Infant Joy" and "Infant Sorrow." While both begin in the voice of a new born infant, only the birth of the first, in Songs of Innocence seems to be heralded as a welcome addition to its family. In the first stanza the infant itself takes the name "Joy," while in the second stanza someone other than the infant seconds the wonder of this child, expressing, again, happiness and great emotion in the form of song.
In "Infant Sorrow," only two short stanzas suffice to tell of the hopelessness of this sullen and unwelcome addition to the family. The quatrains are both in the voice of the infant, and we don't even get the accord of a parental voice agreeing with the child's own self-assessment. The contradiction lies within the fact that the description of the parents actions, though shown in a negative light through the infant's eyes, are actually subject to a wholly different interpretation. Given that only the most drug-addled or masochistic of new mothers would forebear from groaning in the pain of childbirth, perhaps hers was not a groan of dispair but of pain gladly suffered in the delivery of her child. Similarly, the father's weeping may actually have more in common with the child hearing the piper in the "Introduction" to Songs of Innocence; he may weep for joy at the healthy delivery of his child. Swaddling a child was a way to keep them warm and prevent them from constantly suffering from the inborn startle response, and the breast he sulks upon would be a warm and safe source of food and comfort.
All of this seems to point out the idea that the difference between innocence and experience lies not in physical fact but rather in interpretation of circunstances that may, in fact, be similar or even identical.