西周至漢武時期五行說發展脈絡

五行說，其脈絡之演進，係自西周始，學者諸子以「五」組合的因子，充塞於學說中，之後漸次附麗、流變、增長，逮至戰國末年的稷下學者鄒衍，將其蓬勃成五德終始說。究其源，乃是近千年來，上古之人，因對於五種自然物之不可缺，並由賴以存續而衍生之敬畏，依五種物象、物理性質，以類取象，產生釋義並推理，從「自然義」開始，演繹到「人文義」，衍化出五物各擁顏色、方位，而不同方位又各具掌管之帝、神，佐、獸，並掌不同之節氣。逐漸及於天文、地理、季節、耕作、祭祀，乃至於政治、人事、德行、禮儀、軍事、面相等等，成為天命之所歸，政治上改朝換代的依據。然而，從「自然義」的初始，到「人文義」的釋義，卻是逐漸緩進而成，最終演化成為一套繁複的宇宙人文哲學。此一神秘的學說於齊威王時的鄒衍集前人學說之大成，發皇在秦、漢王朝一統天下後，統治者亟需有一套「受命於天」的論證以支撐本朝替代前朝而據有天下的合法性。當現有王朝因德行衰微，導致政治腐敗，民生匱乏，上天即降下災異，或是出現即將崛起的新王朝取而代之的符瑞兆應，前一個朝代無法達到的「德」，即為後一個朝代繼起之「德運」克前朝之德，以「五行相勝」導致「五德終始」的循環秩序，不斷地推進以至於無限。鄒衍之書雖佚，世人無從知曉其文本之全然。但從五行蛻變成為一個複雜的五德終始說的體系，成為皇朝代表的「五德終始」，以「從所不勝」之說，將後起的王朝之所以能代替前朝，乃因「德運」的天命使然。終秦漢兩代，都難以脫離此一神秘的，羼有神話與天人感應的意識形態及其在學術思想中的影響，復經《呂氏春秋》、《淮南子》、《春秋繁露》與司馬遷注入新元素，演化成一套包覆宇宙觀的哲學體系。在政治上的實踐推行，秦始皇為應天命改其先祖原先所認定之金德而為水德，並依水德之理論，施酷法以治天下。漢高祖、文帝均擁兩種以上之德應，及至漢武，在理論、政治、社會、文學、天象等等領域中，不斷地分辨、爭擾、摸索、嘗試，最終亦改祖先之制，以土德定案，完成了五行、五德說，從理論走向實踐的第一次終始的循環（案：即是以文獻學說中：黃帝為土德，歷：木、金、火、水四德，至漢武復以土德定案，成為第一次循環的完成，第二次的起始）。

關鍵字

五行；五德；西周；先秦；秦始皇；漢代

並列摘要

The development of the theory of the Five Virtues Cycle started from Western Zhou, when scholars tended to embellish their propositions with a set of five dimensions, the most notable of which was the “Five Elements.”(Metal, Wood, Water, Fire, and Earth).Sucha conceptgradually developed and transformed, and was eventually expanded into the theory of the Five Virtues Cycle by Zou Yan, a scholar of Jixia Academy in the end of the Warring States period. Ancient people regarded the five natural elements as indispensable; their reliance on the five elements became a respect for these elements. Scholarsin ancient times made interpretations and reasoning regarding the five elements according to their appearance and physical properties. The natural meaning of the five elements was extended into humanity-based meaning, and the five natural elements were also developed to correspond to five colors and directions, ruled by different deities and heavenly beasts, and signify different solar terms. The Five ElementsTheory was then associated withastronomy, geography, seasons, farming, worship, politics, human affairs, virtue, etiquette, military, and physiognomy, even becoming the basis for interpreting the Mandate of Heaven and dynasty transitions. Although the development process from the natural meaning to humanity-based meaning was slow, the theory was eventually expanded into a complex philosophy system regarding the universe and humanity. At the time of King Wei of Qi, Zou Yan developed the theory of the Five Virtue Cycle on the theories of previous scholars. Qin and Han Dynasty united all of China; the emperors required a theory that supported their Mandate of Heaven to legitimize the overthrowing of a previous dynasty and the establishment of the new dynasty. According to the Theory, when a dynasty experiences a moral (virtue)decline, leading to prevalent political corruption and people’ difficultliving conditions, the Heavenwill send natural disasters as punishments, or auspicious signs will appear to indicate the rise of a new dynasty. Thus, aspecific Virtue that a dynasty fails to maintain becomes the founding Virtue of the successor dynasty that overthrowsthe previous one. The continuous generating and overcoming of the Five Elements lead to the cycle of Five Virtues,a cycle that repeats perpetually. Zou Yan’s writing has been lost; therefore, people cannot know the entire content of his theory. Nevertheless, the Five ElementsTheory was transformed into a complex theory of Five Virtue Cycle representing dynastic Mandate of Heaven. The idea of one Element is overcame by another was used to explain that the overthrowing of a dynasty by the successor dynasty was destined by the foreordained Virtue. Both the Qin and Han Dynasty were influenced by this mysterious theory that was mixed with mythology and combined with the concept of interactions between Heaven and Mankind. The Five Virtue Cycle theory also influenced scholars’ thoughts and subsequently evolved into a philosophy of the universe after new ideas from LüshiChunqiu, Huainanzi, Luxuriant Dew of the Spring and Autumn Annals, and Sima Qian were incorporated into it. Regarding political practice, Qin Shi Huang changed the Virtue of Metal, which was designated by his ancestors, to the Virtue of Water in compliance with Heaven’s will. He implemented strict laws and harsh punishments according to the theory of the Virtue of Water. Emperor Gaozu and Emperor Wen of Han both claimed to possess more than two Virtues. However, after numerous investigations, debates, explorations, and trials regarding theories, politics, society, literature, and astronomy,Emperor Wu of Han changed the Virtues determined by his forefathers and decided that the Virtue for the Han dynasty should be the Virtue of Earth. In effect, this completed the first cycle of Five Elements and Five Virtues.(To expound, the first cycle started from the Virtue of Earth at the time of the Yellow Emperor, followed by Wood, Metal, Fire, and Water. Emperor Wu’s choice of the Virtue of Earth signified the end of the first cycle and the beginning of the second cycle.)