Zen Buddhism is often said to be a practice of "mind-to-mind transmission" without reliance on texts-in fact,some great teachers forbid their students to read or write. But Buddhism has also inspired and accumulated some of the greatest philosophical texts of any religion. Two works lie at the center of Zen:The Heart Sutra, which monks recite all over the world,and The Diamond Sutra, said to contain answers to all questions of delusion and dualism. This is the Buddhist teaching on the "perfection of wisdom" and the diamond of its title is said to cut through everything on its way to enlightenment. It is perhaps the most studied of all the sutras, and by one count more than twenty thousand commentaries are noted.