A) At whatever grade level teachers find themselves, from kindergarten to the final class at medical or law school, few moments stir the emotions as deeply as when former students reappear years and often decades later with an update on where their journey has taken them and what resiliencies (韧性)have been the pavement on which they've traveled.

B) So it was when a recent letter came from Kelli Harding, a student 21 years ago in my Peace Studies summer course in Washington. The weekly tuition-free class, in a roomy space that Ralph Nader and his Public Citizen nonprofit group provided, was discussion-based and required no useless homework or exams. Just come in and figure out how to increase peace and decrease violence. And do it today, tomorrow is too late. The course attracted mostly congressional interns (实习 生)，with a few exceptions like Kelli who was in Washington as an AmeriCorps volunteer.

C) Her year-long service included comforting AIDs patients at a free health clinic and delivering meals to the homebound. It was a world apart from her undergraduate days at the University of California- Berkeley majoring in political science. The Washington experience, which Kelli would later call u transformative, was the fuel that carried her into medicine to earn a master's degree in public health from Columbia University and a medical degree from the University of Rochester, and almost two decades of practice

D) Kelli's letter, a literate update on both her personal and professional life, touched my heart, and especially so when saying that two decades later she still has the course text, "Solutions to Violence,“ and that “it remains one of my favorite possessions.^^ She lives in Lower Manhattan with her husband, Padraic, whom she met on a flight to London, and their three boys.

E) If Kelli stands out, it's because she is also a gifted writer. Last month, Atria Books published her book The Rabbit Effect'. Live Longer, Happier, and Healthier with the Groundbreaking Science of Kindness.

F) With a blending of free-flowing confessional prose and scholarly research found in 461 notes, Kelli met my expectations that her ideas and ideals would be sound and singular.

G) Enter the rabbits-not those running around in our woodlands but ones serving in two month-long medical experiments to test the effects of eating a high-fat diet and the connections between cholesterol and heart disease. With similar diets, the expectations were that all the rabbits would have similar cloggings of their arteries （动脉堵塞）.Yet one group had 60% fewer of them.