"Now that you're out of government and making real money, I'm wondering how you're investing. Are you investing in real estate?" Stahl asks.
"There are certain questions I never thought you would ask, but knew that if you did I wouldn't answer. And you just hit one of them," Greenspan says.
What about the stock market?
"I'd just as soon not comment," Greenspan says.
Stahl tried again later by asking about his book advance, reportedly $8 million.
"If you could be paid in any currency, in the world, what would you like to be paid in?" Stahl asks.
"Well, as an economist, I would say I couldn't care less, because I could immediately convert it in the exchange markets to whatever currency," Greenspan says.
Greenspan says it doesn't matter what currency he is paid in. "Key question, basically, is, in what currency do you wish to hold your assets," he explains. "And what I've done is I diversify."
It's not a surprise that he wouldn't say which currencies he's holding.
What is a surprise is how personal and chatty his book is. By his own description "The Age of Turbulence" is a "psychoanalysis" of himself. And analyze this: he wrote it in long hand, in a pretty unusual place.
He admits he wrote 80 percent of his book while in the bathtub.
Greenspan pokes fun at himself, especially in the telling of his romance with NBC newswoman Andrea Mitchell, who's 21 years younger than he is. On their first date in 1984, they had dinner, and he invited her back to his apartment for a bit of "romantic" reading.
"Would you believe he did, he did want to show me an essay he had written," Mitchell remembers.
The topic: anti-trust and monopolies.
"On the Sherman Anti-trust Act of 1890," Greenspan says, laughing.
"You know how to woo a girl," Stahl remarks.
But Greenspan says it worked. They dated for 13 years, before he finally popped the question. "I hinted at it several different times," Greenspan recalls.
"He used Fed-speak. Who knew he was proposing? I couldn't figure it out!" Mitchell says, laughing.
For their honeymoon, he took her to an international monetary conference.
His wonkiness and love of statistics go back to when he was a little boy in Depression-era New York City, when he collected railroad timetables, learned Morse code, and memorized baseball stats.
"You're what we would call today a geek. You're a geek!" Stahl jokes.
"Yeah," Greenspan admits. "You know like some people love reading murder mysteries? I loved reading that stuff."