|Keyword : directional scheme, equinoxes and solstices, four directions, Yao dian, Confucian rituals, the Xi ýý and the He ûú families, sun¡¯s annual motion, diurnal motion, time and space
This study examines the relationship between the equinoxes and solstices and the directional scheme in traditional ritual. For this purpose, the study focuses on ¡°Yao dian¡± èëîð (Canon of Yao), with a view to understanding the principles of directional assignments in Confucian rituals from the perspective of natural science, aided by traditional records of astronomical observations. That the four directions in ¡°Yao dian¡± are related to the equinoctial and solstitial points in the sun¡¯s movement cycle is shown by the tasks and the places assigned to the Xi ýý and the He ûú families. The key directions in ¡°Yao dian¡± are due east and due west, the locations where the sun enters and exits the horizon on the spring and fall equinoxes; the south towards which the sun ascends as it moves from spring equinox to summer solstice; and the north towards which the sun descends as it moves from fall equinox to winter solstice. The tasks and the places assigned to the Xi and the He families also correlate with their family and given names, and yin-yang cosmology plays a key role in identifying these correlations. Moreover, the equinoxes and solstices marked both seasonal divisions (jieqi ï½Ñ¨) in time and cardinal points in space, specifically the four directions corresponding to zi í, wu çí, mao ÙÖ, and you ë· among the 12 Earthly Branches (shier di zhi ä¨ì£ò¢ò¨). These directions were arranged in a circle reflecting the sun¡¯s movement cycle, and constituted a directional framework that comprised yearly cyclical changes in both time and space. The directional scheme in traditional ritual regards the north as the topmost position, and the Clan Law (zongfa ðóÛö) from the Zhou dynasty onward took this as a basic principle of assignment in regard to the order of ranks. Accordingly, it places the summer solstice in the upper part of the celestial sphere, and the winter solstice in the lower part, and thus the positioning of the south and north directions accords with the sun¡¯s declination at summer and winter solstices. The east and west directions pertaining to the spring and fall equinoxes, however, can also be related to its diurnal motion from east to west. Residing in these four directions, the Xi and the He families were tasked with correctly determining the equinox and solstice days by observing the lengths of day and night and the stars in the sky. Their celestial observations were crucial to establishing the annual calendar, which was an important part of the sage king¡¯s government.