By the sixteenth century the discipline and tranquility of the ceremony had become fixed, but the full development of _cha-no-yu _as a vehicle for preserving Zen aesthetic theory was yet to come. Gradually, one by one, the ornate aspects of the earlier Sung tea parties were purged. The idea took hold that tea should be drunk not in a room partitioned off from the rest of the house, but in a special thatch-roofed hut constructed specifically for the purpose, giving tea drinking an air of conspicuous poverty. The elaborate vessels and interior appointments favored in the fifteenth century were supplanted in the sixteenth by rugged, folk-style pottery and an interior decor as restrained as a monastery. By stressing an artificial poverty, the ceremony became a living embodiment of Zen with its distaste for materialism and the world of getting and spending. It remained for a sixteenth-century Zen teacher to bring all the aesthetic ideas in the tea ceremony together in a rigid system. He was Sen no Rikyu (1521-1591), who began as the tea instructor of Nobunaga and continued to play the same role for Hideyoshi. Hideyoshi was devoted to the tea ceremony, and under his patronage Rikyu formalized the classic rules under which _cha-no-yu _is practiced today. The most famous anecdote from Rikyu's life is the incident remembered as the "tea party of the morning glory." As the son of a merchant in a port city, Rikyu developed a taste for the new and exotic. At one time he began the cultivation of imported European morning glories, a novel flower to the Japanese, which he sometimes used for the floral display accompanying the tea ceremony. Hideyoshi, learning of these new flowers, informed Rikyu that he wished to take morning tea with him in order to see the blossoms at their finest. On the selected date, Hideyoshi arrived to find that all the flowers in the garden had been plucked; not a single petal was to be seen. Understandably out of temper, he proceeded to the tea hut--there to discover a single morning glory, still wet with the dews of dawn, standing in the _tokonoma _alcove, a perfect illustration of the Zen precept of sufficiency in restraint.