One of the most stunning mea culpas following the financial crisis was former Fed chairman Alan Greenspan's admission in October 2008 that he had put too much faith in the free market to regulate itself.

His reputation damaged, Greenspan is hitting back.

In an interview with FORTUNE’s Geoff Colvin, Greenspan takes on his critics and says the housing bubble was a “once-in-a-century event.”

Colvin writes, “[Greenspan] believes the case against him is wrong. What is surprising is how deeply he analyzes the debate. He studies the data and is confident it will exonerate him. He is marshaling his facts and will present his data-driven analysis in a 12,000-word article, but hasn't said when. Of course he doesn't like what's happening to his reputation, yet he seems sure that when this recession is past and informed people can look at the whole picture dispassionately, they'll agree that he didn't cause the crisis and couldn't have prevented it.”

Some highlights:

On his “business life,” Greenspan tells FORTUNE: "My actual business life hasn't changed since 1948...The only thing that has changed is my employer...I have fewer meetings and spend less time on uninspiring matters." He describes his current role as “studying data and trying to figure out how the world works.”

On one of his staunchest critics and his good friend John Taylor, who has written scholarly papers intended to show that badly misguided Fed actions under Greenspan created the housing bubble: "He is a very good friend. But his evidence doesn't show what he says it shows."

On the housing bubble: "Mortgage rates started moving down six months before we lowered the Fed funds rate."

On the breakdown in the financial system: "Counterparty surveillance failed to protect the system this time...I always thought it would. I held that belief for 60 years."

On whether tougher regulation is the answer: "I was on the board of J.P. Morgan prior to becoming Fed chairman...I knew what J.P. Morgan knew about Citi, Bank of America, Wells, and others. When I arrived at the Fed, I quickly learned that J.P. Morgan's knowledge of those organizations was far greater than what the Fed knew...Counterparty surveillance will remain the regulators' first line of defense.”

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