William Tell

This is my son's favourite story - the story of how William Tell shot an apple from his son, Walter's, head.
It was the 14th century. Switzerland was invaded by Austria. The invading Austrian governor put his hat on a pole and insisted the Swiss people bow down to the hat. William Tell refused. The governor was incensed. He decreed that William shoot an apple from the top of Walter's head or both dad and the boy would executed.
William took two arrows from his quiver, tucked one in his belt, and shot the apple cleanly.
He said, "Well done Walter, for standing so perfectly still."
"But I knew you wouldn't miss, dad."
The governor asked: "Why did you take two arrows from your quiver?"
And William's thrilling answer?
"If I had killed my son, this arrow was for you."