Just a little parable I thought was good enough to copy onto my website.
The Graybeard engineer retired and a few weeks later the Big Machine broke down, which was essential to the company's revenue. The Manager couldn't get the machine to work again, so the company called in Graybeard as an independent consultant.
Graybeard agrees. He walks into the factory, takes a look at the Big Machine, grabs a sledge hammer, and whacks the machine once whereupon the machine starts right up. Graybeard leaves and the company is making money again.
The next day, Manager receives a bill from Graybeard for $5,000. Manager is furious at the price and refuses to pay. Graybeard assures him that it's a fair price. Manager retorts that if it's a fair price Graybeard won't mind itemizing the bill. Graybeard agrees that this is a fair request.
The new, itemized bill reads...
Hammer: $5
Knowing where to hit the machine with the hammer: $4995