I was convinced that the trading frequency measured a fundamental heartbeat of financial markets. Clearly it reflected the flow of information. It turns out also to be closely related to measures of liquidity.

There are some risks we choose to take because the benefits from taking them exceed the possible costs. Optimal behavior takes risks that are worthwhile. This is the central paradigm of finance: we must take risks to achieve rewards, but not all risks are equally rewarded.

The advantage of knowing about risks is that we can change our behavior to avoid them. Of course, it is easily observed that to avoid all risks would be impossible; it might entail no flying, no driving, no walking, eating and drinking only healthy foods, and never being touched by sunshine. Even a bath could be dangerous.

My mother says that my father truly enjoyed having a son. My two-years-younger twin sisters felt that he didn't quite know how to enjoy them. But I wasn't aware of those things then. So many of my childhood memories involve him. All the excursions into science were shaped by his knowledge and enthusiasm.

We live in a world where there are a hell of a lot of new inputs that need to be factored in to your business. It used to be just about your employees and your customers. Now there are all the issues about global warming, about sustainability, about ethics and now about gender and the distribution of wealth.

I always thought that it was kind of silly that a baseball card could be worth so much money.

As my kids grow up, I think a lot about the lessons and values I want to impart to them. More than any particular skill or even financial support, I believe perseverance and resilience will serve them best, regardless of what curveball life inevitably throws them.

You always question people's intentions. That may be a combination of having money, having fame, and being a little older.