Many people are familiar with Japanese tea ceremony, and its intricate patterns and rituals. The practice became widespread during the 14th century as a form of Zen Buddhist contemplation, in which participants are to become focused on the presence and nature of the objects around them. Each March 27, Rikyu-ki, or the memorial ceremony for Sen no Rikyu, has been observed. Rikyu was a tea ceremony master in the court of the warlord Toyotomi Hideyoshi (one of the three main architects of the unification of Japan under a single government following the centuries-long era of territorial warfare). According to one account, Rikyu subtly rebuked Hideyoshi for his violent excesses, merely by presenting his tea in a black cup. The insult cost Rikyu his life, as he knew it would, but the event caused Hideyoshi deep regret over his actions for many years after.