舊題「呂子」所著《易說》先由「壽山堂」刊刻，此後又收入《道藏輯要》。這是道教文獻中一部重要的《易》學著作，在清代至民國時期有較大影響。但是，長期以來學術界幾乎少有人問津。鑒於該書在近年來逐步引起社會關注，本文通過歷史考察、文本分析，認為該書係清初託名「呂巖」的扶乩降筆之作，雖然其由來頗為神秘，但其宣導「與時偕行」、「修身養性」的「心易」理論卻有積極意義，在中國道教史和中國易學史上都有其獨特價值。

As an important work on the Studies of the Book of Changes (《周易》) among the Daoism literature, Explanation on the Book of Changes (《易說》), by which Master Lu (呂子) was titled as the author according to the traditional conviction, was first inscribed by the Lobby of Longevity Mountain (壽山堂) and later included in the Daoism Cannon as Summary (《道藏輯要》). It had exercised a great influence during the period of Qing Dynasty and the Republic of China, but been lack of academic attention for a long time until recently that it has a strong appeal to the scholars. Through the historical investigation and textual analysis, the authors regard it as a work from the activity of Fuluan (扶鸞), a Chinese traditional magic, by which certain works are produced. Although this book is in connection with a mysterious derivation, its vivid claim, that is Universe Changes as Mind Functioning (心易) consisting of the propositions such as Acting according to changes promptly (與時偕行) and Cultivation of body and mind (修身養性), shares great theoretical significance, which take over a particular occupancy in the history of Daoism and the history of the Studies of the Book of Changes.