Calendar - Rekido

It refers to the study of calendar science and calendar creation, as well as people involved in it. It began in 602 (the 10th year of the reign of Empress Suiko) when Tamafuru, the ancestor of the Yago no Fuhito clan, learned a calendar book brought by the Baekje monk Kanroku. Under the ryo system, it came under the jurisdiction of the Onmyoryo, along with yin and yang, astronomy, and water clocks, and was tasked with measuring the degrees of the sun and moon, creating calendars, and granting time. Japan did not create its own calendar system, but instead compiled an annual calendar arithmetically based on the Chinese calendar system. Calendar science was looked down upon more lightly than onmyodo and astronomy, and gradually declined, so there were no calendar reforms for over 800 years after the adoption of the Senmyo calendar. In the late 10th century, Kamo Yasunori passed on the art of the calendar to his son Mitsuyoshi (939-1015) and astronomy to his disciple Abe no Seimei, and they became the professions of each family. The Kamo (Kotokui) family was a Jige family and served as Onmyō-suke (Assistant to Onmyō) and was a vassal of the Abe (Tsuchimikado) family, who was the Onmyō-kashi (Head of Onmyō). From the early 11th century onwards, errors in calendar calculations were pointed out by Buddhist schools of Shukuyō-dō and Sandō, and eclipses were also forecast by these three groups. The Kamo family died out during the Sengoku period, but was revived in the Edo period and took charge of calendar notes. In the early modern period, it is often called Calendar Studies.

[Yoshiaki Okada]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

暦術・造暦に関する学問、またそれに携わる人物をいう。602年（推古天皇10）百済(くだら)僧観勒(かんろく)が伝えた暦本を陽胡史(やごのふひと)の祖玉陳(たまふる)が習得したのに始まる。令(りょう)制では陰陽(おんみょう)、天文、漏刻(ろうこく)などとともに陰陽寮の管轄で、日月の度数を計り、暦をつくり、時を授けることを任務とした。わが国では独自の暦法を創出せず、中国の暦法によって算術的に毎年の暦を編纂(へんさん)した。暦道は陰陽道や天文道よりも軽視され、しだいに衰えたため、宣明(せんみょう)暦採用後800年以上も改暦が行われなかった。10世紀後半に賀茂保憲(かものやすのり)が暦道をその子光栄(みつよし)（939―1015）に、天文を弟子安倍晴明(あべのせいめい)に伝えて以来、それぞれの家職となった。賀茂（幸徳井(こうとくい)）家は地下(じげ)の家格で陰陽助(すけ)となり、陰陽頭(かみ)となる安倍（土御門(つちみかど)）家の被官となった。11世紀初頭以降、仏教系の宿曜(すくよう)道や算道などから暦算の誤りを指摘され、日食の予報も三者によって行われた。戦国時代に賀茂家は絶え、江戸時代に復活し暦注をつかさどった。近世では暦学と称されることが多い。

［岡田芳朗］

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