"What book?" asked Donald.
"The book that lies all around us, which was written by the Creator of the world," said Uncle Robert. "We are reading a page of it now."
"Just under the current out there," said Frank, "the bed of the river is covered with all kinds of stones. Some of them are as big as these boulders. I suppose the river brought them down."
"What do you think makes the pebbles round?" asked Uncle Robert.
"Maybe the river wears off the rough edges," suggested Frank, thoughtfully.
"Yes," said Uncle Robert, "the current of the river rolls them over and over on the river bed, and they rub and grind against each other."
"What becomes of the stuff that is worn off from them?" asked Frank.
"Don't you see it—there?" said Uncle Robert, pointing to the beach.
"Oh, you mean the sand," said Donald, taking up a handful and examining it.
"Is that the way the nice white sand is made?" asked Susie.