John Hennessy is a martial artist and has been an instructor for over twenty years. He teaches private students in the arts of Kung Fu, Karate, Tai Chi and Jeet Kune Do. In 2011, his first non-fiction book, The Essence of Martial Arts, was published. This updated edition, The Essence of Martial Arts: Special Edition builds on the original with new philosophies and methodologies. It is intended for beginners and experts alike.