In the mid-1960s, Thich Nhat Hanh was a little-known Vietnamese Zen monk, touring the United States on behalf of the cause of peace in his homeland. Jim Forest, a Catholic peacemaker, was asked to accompany him on his speaking engagements. From there emerged a friendship over many decades, in which Jim learned through conversations and daily life about Nhat Hanh's spiritual teachings on mindfulness and the inner peace that is necessary for promoting...