Jack Kornfield (born 1945) is an American writer and teacher in the Vipassana movement in American Theravada Buddhism. He trained as a Buddhist monk in Thailand, Burma and India, first as a student of the Thai forest master Ajahn Chah and Mahasi Sayadaw of Burma. He has taught mindfulness meditation worldwide since 1974. In 1975, he co-founded the Insight Meditation Society in Barre, Massachusetts, with Sharon Salzberg and Joseph Goldstein, and subsequently in 1987, Spirit Rock Meditation Center in Woodacre, California.
https://en.wikipedia.org/wiki/Jack_Kornfield