《想爾注》為東漢晚期的道教經典，是對道家原典《老子》的注釋；在注解《老子》的過程中，有目的地、系統地改造了《老子》文本。它以《老子》為依據，闡發道教的宗教思想，把『道』貫徹到道教的教理及教義之中，以建構自己的宗教理論體系。而「道」的思想在《想爾注》中是一個很重要的哲學範疇，同時「道」的信仰也是全書的主旨和綱領；「道」為天下萬物之本，與「一」、「氣」、「精」、「自然」有著密切的關係；尊「道」奉「誡」，以「道」為依據，詮釋道教的教義，而將「道」宗教化、具體化，「奉道誡，積善成功，積精成神，神成仙壽。」內修積精，外行積善，連守「道誡」。《想爾注》藉《老子》的思想，發展其長生成仙之說，形成信道寶精以求長壽的道教教義，並且對道教「養氣」、「養精」「積善」等成仙的方法和途徑進行論證，使其理論更趨於完備，為道教理論的發展奠定了基礎。本文將從：一、《想爾注》的作者與「想爾」之名；二、「道」的意涵與屬性；三、「道」與「一」「氣」、「精」、「自然」的關係；四、道誡：內修積精、外行積善；五、長生成仙：「長生之道」與「養氣、養精、積善」等面向作一論述，並希冀從此一探究中能對《想爾注》論「道」的思想有扼要的理解。

The Xiang Er Annotation is a Daoist sutra which appeared in the latter period of the Eastern Han dynasty, and was written for the purpose of explaining the original text of Laozi. However, this annotation systematically and deliberately modified the original Laozi in order to adapt the philosophical Dao into religious Daoist teachings, and in this way religious Daoist theory was constructed. In the Xiang Er Annotation, the idea of Dao is an important philosophical concept, and at the same time it serves as religious connotation. The Dao is the root of all things in the world, and it has an intimate relationship with the ideas of ”one”, ”qi” (energy), ”jing” (essence), and ”nature”. According to the Xiang Er Annotation, everything is based on the Dao, and man should worship the Dao and observe its precepts. The Dao hence carries with it religious meaning and actualizes itself as a religious idea. Man should observe Daoist precepts, which teach the accumulation of ”Jing” within man, and the accumulation of goodness he obtains from the outside world. With this method, the Xiang Er Annotation thus developed the goal of pursuing ultimate longevity as celestial being, and this goal has formed the central doctrine of religious Daosim. The Xiang Er Annotation discusses methods for transforming man into a celestial being, with such teachings as ”cultivation of qi”, ”cultivation of Jing” and ”accumulation of goodness”. In all of these teachings, the Xiang Er Annotation establishes the theoretical foundation of religious Daosim. This paper will first begin with the author of the Xiang Er Annotation and the origin of the name Xiang Er; second, demonstrate the meaning and properties of the Dao; third, explain the relationships between the ideas of Dao, ”one”, ”qi”, ”jing”, and ”nature”; forth, illustrate Doaist precepts such as the accumulation of ”Jing” and goodness; and finally, this paper will elucidate the ideas of longevity and celestial being, and describe the methods of ”cultivation of qi”, ”cultivation of Jing” and ”accumulation of goodness”. In the end it is hoped that we may gain a deeper understanding of the Dao in the Xiang Er Annotation.