If I knew where I'd heard it, I'd say but I can't remember. Anyway, here goes:There was a ship owner who had a problem that was causing him much aggravation. He had a new ship due to launch but it wouldn't start. His engineers had tried to fix the problem but it was all in vain.
Eventually, the ship owner called in the local engineering expert, who had, over the years, gained a reputation as the go-to man for any engineering problems.
Later that day, the expert turned up at the ship. For five minutes, he looked at valve and pipes and seemed to be doing advanced calculations or some sort in his head. Then, he bent over, rooted around in his bag, pulled out a hammer and deftly thumped a nearby valve.
To everyones amazement, the ship's bowels coughed and spluttered into life. The ship owner was beside himself with gratitude.
A few days later an invoice landed on the ship owner's desk. The ship owner gasped at the £1000 bill and called the expert complaining that the expert had only worked for ten minutes, yet had charged £1000 for his services. The ship owner demanded an itemised bill.
£0.50 - tapping the valve.
£999.50 - knowing which valve to tap.
