In a book called "The Christian Calling," the author tells of a group of laborers who were working every single day, digging holes five feet deep in the street. The boss didn't tell them why they were digging holes. After they were done digging these holes, he would come over and he'd look at the holes and he would say, "Okay, fill 'er up." They would fill the holes back up again. Finally at noon the men said, "We quit, this doesn't make sense. Give us the money you owe us; we're quitting." The boss asked why they were quitting, and they said, "Well, digging holes doesn't make a lot of sense just to fill them back up again. It's really dumb, and furthermore we look like fools." Then he told them whey they were digging the holes. They were trying to locate a water main.
Source: Stewards Living a God-pleasing Life2008