Mitt Romney debuted the riff last August in New Hampshire and repeated it over and over again at town hall meetings and fancy dinners for many months to come.

The Republican presidential candidate recalled his coming-of-age drives with his parents to national parks — in a Rambler, of course — when they would school him in the values of America by reading from a book, “Men to Match My Mountains,” by Irving Stone.

Then Romney told his audiences about being at a friend’s house when he learned that the book’s title actually comes from a poem, “Men to Match My Mountains,” by 19th-century poet Sam Walter Foss, a New Hampshire native. Romney offered it as a story of American ingenuity — a source of hope that America’s economy, buoyed by entrepreneurs, would come roaring back.

For all the times Romney recited from memory four lines of the poem, however, Romney did not say who had told him about the Foss poem in the first place. He sometimes called his source “a fellow” or “the homeowner.”

But Romney let the secret out — publicly, at least — Tuesday night at a dinner fundraiser here.

“I was actually at the home of Bill Koch, who you may also have heard of, and I mentioned a book I’d read, called ‘Men to Match My Mountains,’” Romney said. “And he said, ‘You know, the title of that book comes from a poem.’ And then he proceeded to recite it, which I thought after, I don’t know, 60 years since high school, was a pretty impressive thing. And I’ve now learned it myself.”

Koch is a billionaire industrialist whose family controls Koch Industries, one of the country’s biggest privately owned companies. His more-famous brothers, David and Charles, have given millions of dollars to help fuel the tea party movement.

But William Koch is a significant contributor to conservative causes as well. He and his company have given at least $2 million to Restore Our Future, a pro-Romney super PAC. And last weekend, Koch hosted a Romney fundraiser at his summer home in Osterville, Mass., on Cape Cod.

Romney mentioned Koch’s role in guiding him to “Men to Match My Mountains” at a small fundraiser last month in Jerusalem, but it was not reported by the journalists covering the event.

Last summer and into the fall, as he tried to solidify his lead in the early primary state of New Hampshire, Romney spoke about “Men to Match My Mountains” at nearly every campaign stop. But he did not volunteer the Koch connection.

At a town hall meeting in Exeter, N.H., last August, Romney brought up the Stone book his parents read to him.

“I was telling that story a week ago Sunday, and in the home of the fellow where I was telling that story, the homeowner got up and he said, ‘I’ll bet you don’t know where the title for that book came from,’” Romney said. “And I said, ‘You’re right, I don’t know where the title came from.’ He said, ‘It came from this poem.’ And then he recited a poem, which I have since learned — it’s only four lines. I can learn four lines.”

And then Romney recited the lines of the Foss poem — just as he would nearly a year later at Tuesday night’s fundraiser at the Petroleum Club in Midland.

Bring me men to match my mountains,

Bring me men to match my plains.

Men with empires in their purpose,

And new eras in their brains.