"A further step in the spread of Zen occurred in the following century when I-k'ung, a Chinese master of the Lin-chi sect, visited Japan. He came at the invitation of the Empress Tachibana Kachiko, wife of the Emperor Saga, during the early part of the Showa era (834-848), to teach Zen, first at the imperial court and later at the Danrinji temple in Kyoto, which the empress had built for him. However, these first efforts in the systematic propagation of Zen according to the Chinese pattern did not meet with lasting success. I-k'ung was unable to launch a vigorous movement. Disappointed, he returned to China, and for three centuries Zen was inactive in Japan." Another opportunity for the Japanese to learn about Ch'an was missed by the famous Japanese pilgrim Ennin, who was in China to witness the Great Persecution of 845, but who paid almost no attention to Ch'an, which he regarded as the obsession of unruly ne'er-do-wells. 3. A number of books provide information concerning early Japanese history and the circumstances surrounding the introduction of Buddhism to Japan. General historical works of particular relevance include: John Whitney Hall, Japan, from Prehistory to Modern Times (New York: Delacorte, 1970); Mikiso Hane, Japan, A Historical Survey (New York: Scribner's, 1972); Edwin O. Reischauer, Japan: Past and Present, 3rd ed. (New York: Knopf, 1964); and George B. Sansom, A History of Japan, 3 vols. (Stanford, Calif.: Stanford University Press, 1958-63). Studies of early Japanese Buddhism may be found in: Masaharu Anesaki, History of Japanese Religion (London: Kegan Paul, Trench, Trubner, 1930: reissue, Rutland, Vt.: Tuttle, 1963); William K. Bunce, Religions in Japan (Rutland, Vt.: Tuttle, 1955); Ch'en, Buddhism in China; Eliot, Japanese Buddhism; Shinsho Hanayama, A History of Japanese Buddhism (Tokyo: Bukkyo Dendo Kyokai, 1966); and E. Dale Saunders, Buddhism in Japan (Philadelphia: University of Pennsylvania Press, 1964). 4. In fact, the popularity of esoteric rituals was such that they were an important part of early Zen practice in Japan. 5. This world is well described by Ivan Morris in The World of the Shining Prince: Court Life in Ancient Japan (New York: Knopf, 1964). A discussion of the relation of this aesthetic life to the formation of Japanese Zen may be found in Thomas Hoover, Zen Culture (New York: Random House, 1977; paperback edition, New York: Vintage, 1978). 6. One of the most readable accounts of the rise of the Japanese military class may be found in Paul Varley, Samurai (New York: Delacorte, 1970; paperback edition, New York: Dell, 1972).