She typed the book from his notes and spoken words.
VOA: special.2009.03.15
He says he doesn't sing the songs that have religious words or meaning, and he notes, rightly, that many of the most famous "Christmas" songs are better described as winter songs many of them written by Jews.
Even when a mother is not actually singing to a baby she tends to speak in a musical way, he says, with the notesand inflections of her words going up and down, and a clear rhythm.