One of the vital aspects of traditional Rinzai Zen koan study in Japan is jakugo, or capping-phrase exercises. When Zen students have attained sufficient mastery of meditation or concentration, they are given a koan (such as the familiar "What is the sound of one hand clapping?") to study. When the student provides a satisfactory response to the koan, he advances to the jakugo exercise-he must select a "capping phrase," usually a...