"Christopher trying his best to entertain them by reading to them from Mother Goose."

Mother Goose is a imaginary author of a collection of tales and poems for children. She can be traced as far back as the mid-17th century and some believe she was a real person.

The Real Mother Goose book
Creative Commons AttributionThe Real Mother Goose book - Credit: "T"eresa
Christopher is probably reciting to the twins the book of short poems entitled The Real Mother Goose, published in 1916. It is the one American readers are most familiar with.