Book Traces Friendship Between Math Teacher Joffray ’50 and Student

In The Calculus of Friendship (Princeton University Press), Cornell University professor Steven Strogatz chronicles the moving story of the friendship he developed with his former high school math teacher, Don Joffray ’50, over 30 years through the exchange of letters between them. For a long time, their friendship revolved almost entirely on a shared love of calculus.

Joffray goes from the prime of his career to retirement, competes in whitewater kayaking at the international level, and loses a son. Strogatz matures from high school math whiz to Ivy League professor, has a failed marriage, and experiences the sudden death of a parent. Eventually they get to know each other better beyond the world of mathematics.

In the prologue, Strogatz writes: “Like calculus itself, this book is an exploration of change. It’s about the transformation that takes place in a student’s heart, as he and his teacher reverse roles, as they age, as they are buffeted by life itself.” Their shared love of calculus becomes “a constant while all around them is in flux.”

A video about the book is on YouTube.