太乙術數是一門秘術，自古以來識者不多，可供研究之參考資料很缺 乏。《欽定四庫全書》收入一部經後人增補之唐代典籍，《古今圖書集成》亦有 明代之著作。現存關於太乙術數之文獻不早於唐代。《南齊書．高帝本紀上》史 臣曰章引述編者蕭子顯應用太乙術數，以暢論六百七十九年間之有關國家興亡大 事。本文試由蕭子顯之推算結果，倒算出南北朝時代編者所採用之推算方法;因 而證實唐代與明代典籍所載太乙術數最少可以追溯至南北朝。而且二者內容皆一 致，表示皆出自同一系統。本文又試以編者原用方法再推算史臣曰章各條，發覺 現存刻本原文略有誤漏，術數偶爾也可以應用在校讎學上。現存唐明兩代典藉所 載太乙術數之操作皆以「上元積年」為距數，本文指出在運用上可以省略引用「上 元積年」之繁雜操作。本文簡單介紹太乙術數之歷史及其演變，並談及歷史上術 數在傳統之天人合一觀念下所扮演的角色。本文所說之太乙術數已經受時代淘 汰，但此術有一支流可能受到從印度與西亞傳入中土之希臘占星學影響，演變為 現代流行在華人社會中之紫微斗數。

　　　　　The Tai-i method of divination was an arcane art, known only to the very few andprecious little reference material is available for research. A T'ang text on the method withlater additions is preserved in the Ch 'in-ting Ssu-k'u ch'uan-shu, while a Mmg text isincluded in the Ku-chin t'u-shu chi-cheng collection. From these texts alone the T'ai-imethod cannot be traced earlier than the T'ang period. In the Historiographer's Remarkssection in the Chronicle of Emperor K.ao-ti in Nan-Ch 'i-shu the author Hsiao Tzu-hsienemploys the T'ai-i method to rationalize important political events spanning a period of sixhundred and seventy-nine years. This paper reconstructs the method used by Hsiao Tzu-hsien from the text of the Nan-Ch'i-shu and compares the interpretations made with those ofthe T'ang and Ming texts, and shows that they are essentially identical. Hence this method can be traced to a date not later than the time of the Six Dynasties. In recalculating every item in the section, some minor mistakes and omissions in the present printed editions of the Nan-Ch 'i-shu reveal themselves, demonstrating an unexpected application of a so-called pseudo-science in a serious scholarly work of textual collation. The texts available to us show the dependence of the method on an accurate knowledge of the Great Epoch-the interval of time since the sun, the moon and the planets were together last in conjunction. This paper shows that the rather clums> procedure of using the Great Epoch can be dispensed with in arriving at the same results in the Nan-Ch'i-shu. This paper also gives a brief history of the T'ai method of divination and discusses the implications of the traditional philosophical view of harmony between heaven and man on the pseudo-science's. Although the T'ai-yi method is now gone and almost completely forgotten, it is plausible that a tributary that came under the influence of Polemic astrology, introduced to China via India and West Asia, has developed into the modern system of Tzu-wei tou-shu astrology,which is popular among Chinese communities in many parts of the world.