A building contractor was being paid by the week for a job that was

likely to stretch over several months. He approached the owner of

the property and held up the check he'd been given. "This is two

hundred dollars less than we agreed on," he said.

"I know," the owner said, "But last week I overpaid you two hundred

dollars, and you never complained."

The contractor said, "Well, I don't mind an occasional mistake. But

when it gets to be a habit, I feel I have to call it to your attention."