Rishu (), lit. "Day Book," is a genre of hemerological texts that circulated widely in China from the late Warring States Period to the Western Han dynasty.[1] Rishu is also the name of one of the primary literatures for the schools of orthodox Shingon Buddhism of Japan. This term finds its first evident presence dated back to 217 BCE in China.[2]
In Mainland China, the Rishu (Chinese: 日書) "Day Book" is one of the pieces of literature discovered in late Warring States period[3] tomb libraries which has confirmed the Baopuzi description of Yubu as a series of three steps. It has great cultural significance in ancient and medieval China. It is an almanac or hemerology which is one of the Shuihudi Qin bamboo texts recovered in 1975 in Shuihudi, Hubei, from a tomb dated 217 BCE. Donald Harper (1999:843) believes that for describing texts like the Rishu Chinese: 日書, which determine lucky and unlucky days on sexagenary cycle numerology without reference to astrology, "hemerology" is a more accurate translation than "almanac" (typically meaning an annual publication for a single calendar year).
The Rishu has one occurrence of Yubu san Chinese: 禹步三, "'Steps of Yu, three times", and one of Yubu sanmian Chinese: 禹步三勉, "Steps of Yu, three exertions". This is consistent with the Baopuzi descriptions of Yubu in terms of sanbu "three steps" and jiuji Chinese: 九跡, "nine footprints/traces," where each "step" was composed of three separate steps. Andersen (1989:17) notes that the term Sanbu jiuji was later used synonymously with Yubu.
Yu is closely associated with travel in the Rishu (Harper 1999:872). The section titled "Yu xuyu" Chinese: 禹須臾 "Promptuary/Instant of Yu" begins by listing the stem and branch sexagenary cycle in five groups of twelve signs each, and gives, for the days in each group, a certain lucky time of day to safely begin a journey. This section concludes with a ritual to be performed before going out of the city gate.
Isabelle Robinet (1997:39) says this text lets us reconstruct the connection between "exorcistic practices intended to ward off harmful demons, and therapeutic practices intended to ensure good hygiene and good physical balance", in other words, "the evolution of exorcism toward medicine, a shift from conceiving sickness as caused by demons to seeing sickness as the result of an imbalance".
In Japan, the term has more varied and widespread significance in different aspects of its culture. The most prominent of them are listed below: Rishu-kyō (the Adhyardhaśatikā Prajñāpāramitā Sutra) is one of the primary literature for all the schools of orthodox Shingonshu. The others being the Mahavairocana Tantra, the Vajrasekhara Sutra, and the Susiddhikāra Sūtra (Soshitsuji-kyō 蘇悉地経). These are the four principle texts of Esoteric Buddhism. They are all Tantras, literally "treatise". These texts played a vital role in Tachikawa-ryu.[4] But according to the author and Tachikawa-ryu historian, John Stevens as well as James Sanford, the most important text to the ryūha (流派) perhaps, was the Sutra of Secret Bliss (ca. 1100). This sutra contains the school's general teachings concerning sexuality and its role in reaching enlightenment. It was Rishu-kyō.
There are several places across East Asia associated with this term in different aspects.