What was later revealed about the story?

It was later revealed that Helen had a similar story read to her.

Miss Sullivan had never heard of "The Frost Fairies" or of the book in which it was published. With the assistance of Dr. Alexander Graham Bell, she investigated the matter carefully, and at last it came out that Mrs. Sophia C. Hopkins had a copy of Miss Canby's "Birdie and His Friends" in 1888, the year that we spent the summer with her at Brewster. Mrs. Hopkins was unable to find her copy; but she has told me that at that time, while Miss Sullivan was away on a vacation, she tried to amuse me by reading from various books, and although she could not remember reading "The Frost Fairies" any more than I, yet she felt sure that "Birdie and His Friends" was one of them.