Eisai was instrumental in introducing tea consumption to the samurai class. He presented a version of his "Kissa Yōjōki" in 1214 to "shōgun" Minamoto no Sanetomo, who had been suffering from a hangover after drinking too much "sake". Eisai also served tea to the young shōgun. Zen Buddhism, as advocated by Eisai and others, also became popular during this period, particularly among the warrior class. The Zen monk Dōgen promulgated a set of rules for Buddhist temples based on "Rules of Purity for Chan Monasteries", a Chinese text of 1103. Dōgen's text included notes on etiquette for the serving of tea in Buddhist rituals. Tea was considered central to practitioners of Zen Buddhism. Musō Soseki went as far as to state that "tea and Zen are one".