學界過去多從亡國易代的角度，解釋宋元之際士人為求隱逸避世，而走向親道、入道。本文嘗試另闢蹊徑，從思想史的視角探考其原因。首先介紹朱熹（1130-1200）的易學觀，說明他詮釋易圖象數的方式，已跳脫傳統格局，為突破儒、道的知識界線，創造了思想上的條件。以《周易參同契》的研究為例，可以發現朱熹及其周邊士人，因易學及宇宙論上的興趣，而探討《參同契》的象數理論；但在考究《參同契》的同時，也有涉入煉丹術的情況。南宋中期以降，有越來越多的士人在易學研究上追隨朱熹的腳步，利用易圖及象數推闡宇宙原理，而不只是專注於《周易》文本的注釋。這股研究趨向時常誘發士人們走進道家的知識領域，探索道經、丹學中的象數學說，以強化易學描述及推導自然原理的功能。最終，以易圖象數作為媒介，逐漸在理學和道家之間創造出共通的世界觀和概念語言。這也為宋元之際士人的親道、入道，提供了重要的思想基礎。

In the past, historians tended to interpret the Confucian intellectuals’ engagements with Daoism as an attempt to stay isolated from the secular world, and considered it a response to the dynastic change from the Song to the Yuan period. From the perspective of intellectual history, this essay attempts to provide an alternative interpretation. To begin with, Zhu Xi’s theory of Yi Xue (study ofthe Book of Change) will be elaborated. Specifically, this essay argues that the way he interpreted Yi-Tu and Xiang-Shu broke the boundary between Confucianism and Daoism. Taking the study of the ZhouyiCantongqi for example, in their studies of Yi Xue Zhu Xi and his fellows obviously took note of the Xiang-Shu theory from the Cantongqi. Moreover, they were also involved in the practice of alchemy when studying the Cantongqi. After the mid Southern Song, more and more intellectuals followed in Zhu Xi’s footsteps and sought the principles of the universe usingYi-Tu and Xiang-Shu, instead of relying on the Zhou Yi alone. This approach further motivated other intellectuals to investigate the theory of Xiang-Shu in other Daoist classics and the alchemical traditions. They did so with the purpose of enhancing the explanatory power of Yi Xue in terms of the principles of the universe. Eventually, functioning as a medium, Yi-Tu and Xiang-Shu helped create a common worldviewas well as the concepts and vocabulary shared by Daoists and Neo-Confucians. This provided an intellectual foundationin the Song-Yuan period, for the Confucianintellectuals engaging with Daoism and sometimes even becoming Daoists themselves.