One of the most common causes of failure is the habit of giving up in despair at the first sign of temporary defeat. Every one of us falls into this trap now and then.

In the gold-rush days, R. U. Darby’s uncle was seized by “gold fever” and went west to dig and grow rich. He had never heard that more gold has been mined from the minds of men than was ever dug from the earth.

After weeks of hard labor under brutal conditions, he was rewarded with a glint of shining ore. He needed machinery to bring it to the surface, so he quietly covered the mine and returned home to Williamsburg, Maryland. He told his relatives and neighbors about the rich vein he had struck. Together they pooled the money for the machinery and shipped it out. The uncle and Darby went back to the mine. The first carload of ore was sent to the smelter, and the results showed they held one of the richest deposits in Colorado. A few more carloads would clear their debts — then the great profits would roll in.

The drills bit deeper. The hopes of Darby and his uncle climbed higher. Then something happened: the vein of gold vanished. They had reached the end of the rainbow, and the pot of gold was no longer there. They drilled on, desperately trying to find the vein again, but all in vain. At last they decided to quit.

They sold the machinery to a junk man for a few hundred dollars and took the train home. The junk man called in a mining engineer to examine the mine and do some figuring. The engineer concluded that the venture had failed only because the owners did not understand “fault lines.” His calculations showed the vein lay just three feet from where the Darbys had stopped digging. And that is exactly where it was found.

The junk man took millions of dollars in ore from that mine — because he had the sense to seek expert advice before giving up.

Long afterward, Darby recovered his loss many times over, when he discovered that desire can be turned into gold. The discovery came after he went into the business of selling life insurance. Remembering that he had lost a fortune by stopping three feet short of gold, he put the lesson to work. “I stopped three feet from gold,” he told himself, “but I will never stop when people say ‘no’ as I ask them to buy life insurance.”

Darby became one of a small group of men who sold more than a million dollars of life insurance a year. He owed his persistence to the lesson he had learned from his quitting in the gold-mining business.

— Napoleon Hill, “Think and Grow Rich”