Raku is a low-fired ceramic ware first produced by Sasaki Chōjirō (d. 1592) in the 16th century in Kyoto. Under the encouragement and patronage of his close friend, tea master Sen no Rikyū, he crafted a style of bowl which was very much unlike the colorful Chinese-influenced ceramics of the time. In stark contrast, Chōjirō's works were mostly monochrome black or red and devoid of any decoration or sense of movement.
Before this time in history, the drinking of green tea tended to be a festive affair enjoyed mostly by the nobility. They imbibed the emerald brew with great pomp and pageantry, often holding lively tea tasting competitions. Later, as Zen Buddhism (an import from China) took root in Japan, the event became a much more solemn, ritualized ceremony called sadō or chanoyu.
It was Rikyū who melded principles of Zen and Taoism with chanoyu to create the comprehensive art of wabi-cha - that is, tea ceremony upon which great importance is attached to simplicity, austerity, and quiet appreciation. Chōjirō, in turn, sublimated his own artistic impulses to create bowls which embodied Rikyū's tea philosophy. His creations so pleased warlord Toyotomi Hideyoshi that Chōjirō's successor received a golden emblem with the kanji character for raku (seen below), meaning "pleasure," thus officially establishing the Raku dynasty of potters.
Although the appellation "Raku" is reserved for those works made by Chōjirō and his lineage (the current Raku grandmaster is Kichizaemon XV), the term is used by a number of contemporary Japanese potters who adhere to the same forming, glazing and firing techniques.
