天行有常與休咎之變──中國古代關於日食災異的學術、禮儀與制度

Scholarly Discourses, Rituals and Institutions Related to Solar Eclipses in Ancient China

災異論講「變」，科學研究「常」，兩者之間存在矛盾。本文以中國古代日食推步技術的發展與相關的學術、禮儀、制度變化爲中心，研究「天行有常」與「休咎之變」矛盾背後學術與政治的互動。隨著日食推步技術的發展，唐代官方經學已經承認日食是曆數之常，但仍强調聖人神道設教之意，要求在意識形態領域堅持災異休咎說。與此同時，天文曆算由於自身的有限性，也需要引入政教休咎的因素，與「曆數」配合，完整地解釋「天道」。因此，在曆法層面，災異論與日食推步得以共生不悖。日食預報的展開沒有終止天人感應論，反而在唐代造成日食祥瑞說以及相關的表賀、入史等制度，影響下及清代。日食祥瑞說與災異論一樣，都以「休咎之變」爲理論基礎，而並未固執一端，堅持「天行有常」。與此相應，日食救護禮儀的實際作用雖然不再爲人們所堅信，但作爲一種儀式性的存在，仍具有「敬畏天戒」的象徵意義，因而得以長期保留。儒家意識形態中的神道設教之義，很大程度地抵消了「天行有常」的認識在政治制度和政治活動中的影響。

There is always a conflict between science and zaiyi theory; the latter focuses on anomalies while the former only concerns itself with the laws of nature. This essay focuses on developments in solar eclipse calculation, and related changes in the scholarship, rituals and institutions of ancient China. This essay tries to explain the interactions between scholarly discourses and politics in light of the contradiction between the laws of nature and anomalies, which were recognized as the result of good or evil human behaviors. Though as the ability to calculate and predict solar eclipses improved, intellectuals in the Tang dynasty held that solar eclipses followed the laws of nature, they emphasized the profound significance of “teachings through mystical methods,” and resolutely insisted upon the validity of zaiyi theory as part of their ideology. Meanwhile, astronomy and calendric systems still had unavoidable flaws in the Tang dynasty; thus, they also needed to be complemented by zaiyi theory in order to fully interpret the manifestation of Heaven’s will. For these reasons, zaiyi theory and solar eclipse calculation could coexist in the calendric system. Advances in the prediction of solar eclipses did not do away with the theory of “relations between Heaven and human beings.” Rather, they brought about consequences such as intellectuals viewing solar eclipses as some kind of auspicious sign and applying this opinion in decrees and historical records, consequences which continued until the Qing dynasty. Viewing solar eclipses as auspices is the same as viewing them as catastrophes in that it is premised on the notion that anomalies are caused by good or evil human behavior, rather than emphasizing the order of nature. Correspondingly, the efficacy of the ritualistic practice of “rescuing” solar eclipses was by then already disputed, but still had its symbolic significance. To a large extent, the “teachings through mystical methods” theory in Confucianism counteracted the influence of “the order of nature” in the political system and political activities.