Once a man planted a garden. He watered it well and was delighted when shoots emerged. As weeks passed, those shoots grew into plants. Every day he watered and weeded, and his garden grew until one day he was ecstatic to see plants bearing fruit and vegetables. Now I can take a few days’ rest, he thought, content in knowing his efforts would produce a harvest. He left the produce to ripen on the plants.

A few days later, he went to his garden and was dismayed to see that what he had hoped to eat had already been eaten. On every plant was evidence of hungry rodents and rabbits who had raided his crop. So he decided to erect a fence.

A few days later, the man again went to his garden and saw the same thing. So he put up another fence, another, and another. Every time he checked, he found vermin had raided the garden. Finally he realized critters could go over, through, or under each fence. So he built a brick wall over a 10-foot-deep concrete foundation. He was sure nothing could get ...