April 23, 2026
In 1995, I started as an undergraduate at Tsinghua University in Beijing. I was in the School of Economics and Management. My advisor recommended this book to me — Brownian Motion and Stochastic Flow Systems by J. Michael Harrison [the Adams Distinguished Professor of Management, Emeritus, at Stanford GSB]. The first time I heard of Stanford GSB was probably through that book.
Editor’s Note
In this ongoing Stanford Business series, we visit Stanford GSB professors’ offices and ask them to share the stories behind some of their favorite mementos.
Zhiguo He is the James Irvin Miller Professor of Finance at Stanford GSB.
I wanted to read this book, obviously. I saw an original copy in the university library, but I also wanted to own one. I don’t remember what the price was, but I could not afford it. Basically, we were just too poor to buy books like that. This was before the economy took off — at that time, China was a totally different country.
Back then it was quite common for people to make a copy of a famous book and then sell it on the street or the black market. I found this copy of the book and bought it. I used to joke that if a copy of your book was being sold on the street, that meant it must be really good.
Brownian Motion and Stochastic Flow Systems is extremely dense. Reading it was the first time I really understood Brownian motion. There are certain things that only exist in people’s minds; Brownian motion is one of them. The first time I’d heard about it was through Einstein. Brownian motion describes random movement — originally the movement of pollen in water, a very small thing, and extremely random.
In the world of economics, you can observe Brownian motion in the behavior of stock market price movement, because at any point in time you don’t know whether it’s going up or down. It’s extremely volatile.
Today, I’m happy to own an authentic copy of the book, because it’s a useful book. I still constantly refer to it. It relates to the tools we use in our research, especially on the theory side. You look around the world and try to abstract things and put them into models.
When I first came to the GSB, I met Michael Harrison, but I never mentioned the book to him. When last year’s Faculty Celebration of Scholarship was being planned, I told him, “I’m going to say something about you.” I brought my old copy of his book and told its story at the conference for the finance group. I was very flattered that he was there. This book was the first time Stanford GSB had a concrete influence on me. — Told to Dave Gilson
For media inquiries, visit the Newsroom.
