In the early Buddhist saṅgha, monks and nuns gathered at the full and new moons to confess wrongdoing and atone for their actions. On these occasions, the Prātimokṣa (the rules of monastic discipline) was recited, and laypeople were also given the opportunity to follow the same rules as ordained Buddhists for a period of twenty-four hours. In Pāli, these days were known as Uposatha.

The practice of Uposatha spread to other Buddhist countries and, in Japanese Sōtō Zen, evolved into Ryaku Fusatsu, which may be translated as “abbreviated” or “simple ceremony for continuing to do good.” The elements of confession and avowal from the original ceremony remain, but instead of the Prātimokṣa, there is a recommitment to the sixteen Zen precepts, which are received at Jukai and during Shukke Tokudo (home-leaving ordination). We acknowledge our past failings and vow to do better in the future, all while recognizing our frail human nature and casting all into Emptiness. In this way, our atonement is sometimes described as our “at-one-ment.”