Robert J. Shiller

"I was reminded of how much I had misjudged the potential the profession would see in the time series rational expectations models. When I, as a graduate student at the Massachusetts Institute of Technology (MIT) around 1970 did some work on the econometrics of rational expectations time series models, I felt rather apologetic about the extreme assumptions in the models. I did not expect others to regard them as anything more than a passing gimmick. Richard Sutch had just written in his MIT doctoral dissertation (1968) an exposition of the coefficient restrictions implied for time series representations of long-term and short-term interest rates, but he never bothered to publish this work. I remember conversations with him and others about rational expectations models, and I did not come away thinking they were the wave of the future."

"To understand the economy then is to comprehend how it is driven by the animal spirits. Just as Adam Smith’s invisible hand is the keynote of classical economics, Keynes’ animal spirits are the keynote to a different view of the economy — a view that explains the underlying instabilities of capitalism."

"This [covariance] is something that is not in the habit of thinking of most amateur investors. They look at their investments one at a time, and they don't, you always have to go back and say, what's the covariance? That's what really matters for what happen to your portfolio. Because when you invest in a lot of companies that are all the same, you're asking for trouble, because the whole thing is going to either blow up or succeed. And you can't live like that. You have to be looking for low covariance."