In his own words
Introduction
Piping down the valleys wild, Piping songs of pleasant glee,On a cloud I saw a child, And he laughing said to me:
"Pipe a song about a Lamb!" So I piped with merry cheer."Piper, pipe that song again;" So I piped: he wept to hear.
"Drop thy pipe, thy happy pipe; Sing thy songs of happy cheer!"So I sang the same again, While he wept with joy to hear.
"Piper, sit thee down and write In a book, that all may read."So he vanish'd from my sight; And I pluck'd a hollow reed,
And I made a rural pen, And I stain'd the water clear,And I wrote my happy songs Every child may joy to hear.
The book opens with a piper meeting a child on a cloud. The child asks for a song, then asks for it to be written down. All of Innocence presents itself as songs a child asked for.