in the kamakura period, a buddhist monk, eisai (1141–1215), and his follower, dogen, first brought tea "(maccha)" to japan. he had learned about tea on a visit to china. eisai taught people to grow the tea plants, and how to prepare the tea leaves. people drank tea for its benefit as a medicine rather than as a refreshment. tea-drinking gradually spread as part of zen buddhism. the tea ceremony was part of the training for mental discipline. green tea kept the mind pure and relaxed, an effect caused by the caffeine in the tea. the custom of drinking tea gradually spread throughout japan.