"....We don't know when people started to celebrate it for the first time.
But it is clear that this holiday began a few years after the first Mother's
Day. Some say the idea came from Mrs. Sonora Smart Dodd. Her father took good
care of the six children in her family after her mother died young. So Mrs. Dodd
wanted to show thanks to her father in the same way people celebrated Mother's
Day...."
In which part of the book would you most likely find these sentences?