After I started going to school my father scarcely talked any more. I was very intoxicated by the new game of spelling; my father had little skill for it (it was my mother who wrote our letters) and was convinced I was no longer interested in hearing him tell of his adventures during the long weeks when he was far away from the house.
One day, however, he said to me: "The time's come to show you something."

He asked me to follow him. I walked behind him, not talking, as we had got in the habit of doing. He stopped in the field before a clump of leafy bushes.
"Those are called alders," he said.
"I know."
"You have to learn how to choose," my father pointed out.
I didn't understand. He touched each branch of the bush, one at a time, with religious care.
"You have to choose one that's very fine, a perfect one, like this."
I looked; it seemed exactly like the others.

My father opened his pocket knife and cut the branch he'd selected with pious care. He stripped off the leaves and showed me the branch, which formed a perfect Y.
"You see," he said, "the branch has two arms. Now take one in each hand. And squeeze them."
I did as he asked and took in each hand one fork of the Y, which was thinner than a pencil.
"Close your eyes," my father ordered, "and squeeze a little harder.. . Don't open your eyes! Do you feel anything?"
"The branch is moving!" I exclaimed, astonished.