CALENDRICS ORIGIN

Origin of Calendrics

Measured by ecliptic longitude and the tropical year; four Lis with equinoxes and solstices shape seasonal order.

Core Concepts

Tropical Year System

Dates largely fixed in the Gregorian calendar; transit moments align with the sun’s annual motion.

Ecliptic Longitude Scale

15° per term: Lichun 315°, Chunfen 0°, Xiazhi 90° — unified spatial-temporal scale.

Four Lis · Equinoxes · Solstices

Four Lis mark starts; equinoxes and solstices are midpoints, forming an orderly seasonal frame.

Evolution Timeline

Nascent Stage (Xia-Shang to Western Zhou)

Emergence of two equinoxes & two solstices

Xia's Jia Xiazheng records phenophase-season connection; Oracle bone script mentions winter/summer; Western Zhou used gnomon to determine solstices/equinoxes; Gonghe's observation platform (Dengfeng) is physical evidence.

Gnomon shadow observation, Big Dipper observation to mark seasonal nodes

Development Stage (Spring-Autumn to Warring States)

Formation of "Eight Nodes" (two equinoxes & solstices + four Lis)

Spring-Autumn period refined equinoxes/solstices; Late Warring States, Lushi Chunqiu clearly named eight nodes (Lichun, Lixia, etc.), beginning fine-grained seasonal divisions.

Mature soil-gnomon observation; combined with phenology & agricultural need for finer nodes

Standardization Stage (Qin-Han Dynasty)

Complete 24 terms established and integrated into calendrics

Early Western Han, Huangdi's Tianwen first records complete 24 terms matching modern names; 104 BCE, Taichu Calendar officially incorporates them into state calendrics, defining astronomical positions & agricultural guidance.

Refined astronomical observation; "Equal qi method" (15 days per term) becomes standard

Refinement Stage (Tang-Song to Ming-Qing)

Increased precision in solar term calculation

Tang Dynasty's Dayan Calendar optimized calculations; Yuan Dynasty's Shoushi Calendar adopted "Fixed Qi" method (15° ecliptic longitude per term); Qing continued, matching modern standards.

Advanced astronomical-calendrical computation; precise sun ecliptic position localization

Heritage Stage (Modern Era)

Inscribed as intangible heritage, globally disseminated

Inscribed (2016) on UNESCO List of Intangible Heritage of Humanity, becoming globally shared temporal-cultural heritage.

Modern meteorology integrated with traditional wisdom for scientific education & cultural dissemination

Authoritative Sources

Jia Xiazheng

Xia-Shang Period (Traditional)

Monthly records of celestial phenomena, phenophase, agriculture; includes phenophase descriptions linked to solar terms

China's earliest phenophase calendar; provides original basis for solar term origins

Shang Shu (Book of Documents)

Spring-Autumn Period

Records "zenith sun" (spring equinox), "longest day" (summer solstice), "midnights" (autumn equinox), "shortest day" (winter solstice)

Earliest textual record of equinoxes/solstices; establishes astronomical & political significance, foundational for later calendrics

Yi Zhou Shu (Lost Books of Zhou)

Warring States Period

Five days per pentad, three pentads per term; records 24-term to 72-pentad correspondence, refines phenophase assessment standards

First systematic linkage of terms to pentads; establishes "term-pentad" framework

Lushi Chunqiu (Spring & Autumn of Lü)

Late Warring States

Clearly names eight nodes (Lichun, Chunfen, Lixia, Xiazhi, etc.); integrates terms with agricultural activities

Transitional text bridging early & later traditions; provides framework for complete 24-term system

Huainanzi (Masters of Huainan)

Early Western Han

Complete record of 24-term names, dipper positions, musical correspondences; names match modern usage exactly

Earliest extant complete 24-term record; core basis for solar term standardization

Taichu Calendar

Western Han (104 BCE)

Compiled by Deng Ping et al.; formally inscribes 24 terms into state calendrics; specifies astronomical positions & agricultural guidance

Marks terms as official calendrical component; influences all subsequent dynasties

Hanshu (Book of Han)

Eastern Han Period

Records term-music & term-calendrical correlations; refines astronomical & mathematical computation methods

Perfects term theoretical framework; advances astronomy-calendrics integration

Yueling 72-Pentads Compendium

Yuan Dynasty

Detailed annotations of phenophase traits for each 24 terms (three pentads per term); becomes standard reference for later pentad interpretation

Standardizes phenophase expression; provides authoritative interpretation for cultural dissemination

Shoushi Calendar

Yuan Dynasty

Adopts "Fixed Qi" method for term division; 15° ecliptic longitude per term; increases calculation precision

Establishes modern term division standard; continues to present day

China Meteorological Yearbook

Modern Era

Annually releases precise term transit times & climate characteristic data; authoritative reference for modern term applications

Integrates modern meteorology; provides scientific verification basis for term data

Calendrics Manifesto

“We understand time by order and measure seasons by scale; calendrics is the language between civilization and the cosmos.”