FORTUNE — Larry Summers made waves at Fortune’s Brainstorm Tech conference last week with his candid comments about the Winklevoss twins when asked about his scene in the movie The Social Network. The Harvard professor also talked about how he sees a sort of Financial Armageddon on the horizon as the debt talks break down in Washington.
During his wide-ranging interview with the Aspen Institute’s Walter Isaacson, Summers, who joined the venture capital firm Andreessen Horowitz as special adviser last month, revealed stark differences in management styles between Presidents Clinton and Obama.
Here is an excerpt from the interview:
Summers: Okay. So you’re working for Bill Clinton. Well, let’s do it differently. Let’s do it the other way. You’re working for Barack Obama. If you have a meeting scheduled at ten o’clock, there’s a 25% chance that the meeting will begin before ten o’clock, and there’s a — you know what’s coming, and there’s a 70% chance that the meeting will have begun by 10:15.
If you wrote Barack Obama a memo before the meeting, it is a virtual certainty that he will have read it. If you seek to explain the memo you wrote to him during the meeting, he will cut you off, and he will be irritated. He, as the leader of the meeting, will ask one or two questions to kick the tires, but will basically focus on how whatever subject you’re talking about fits with the broad vision and approaches of his presidency.
He will basically take the attitude if you’re his financial adviser, that if you can’t — it’s up to you to figure out whether preferred stock or subordinated debt is the appropriate financial instrument for your bailout, and that if he doesn’t trust you to figure it out, he’ll get a new financial adviser, but that is not the question on which he is going to spend time.
So it’s a very focused executive, big picture guidance, disciplined approach. At the appointed time, his secretary will come in and will bring a card that says it’s time for his next meeting, and you will be out of that office within five minutes. It is a certainty. That’s working for Barack Obama, and it is a wonderful experience.
Working for Bill Clinton is also a wonderful experience. It is a different experience.
The probability that your meeting will begin before ten o’clock is zero.
The probability that there is compensation for the fact that your meeting will begin late, it is virtually certain to end late. Bill Clinton has a 30% chance of having read your memo before the meeting. Bill Clinton will, however, with near certainty, have some set of quite detailed and thoughtful perspectives to offer on your topic.
He will say things like “I was in the White House library reading the Journal of Finance, and there’s some really interesting thinking about the role of dividends in the system.” “I went to a conference at the Brookings Institution 11 years ago, and do you know that there’s a really interesting experiment with providing credit access in Tennessee?”
“Did you read the latest issue of — the Asian edition of The Economist? It had a perspective on Thailand that you might want to think about.” There was a stunning, I mean you know, while he wasn’t reading your memo, it wasn’t that he wasn’t doing anything about it.
So it was a very different kind of experience that was also extraordinary in its way. I think the nation has been fortunate to have two such thoughtful, purposeful, highly intelligent and focused people, who have served as President, and it’s certainly been my good fortune to work for both of them, with their rather different styles.