敬天的思想及儀式自遠古便已產生了，但「天」的蘊含卻發生了很大改變，擇要而言，即：人格意志化的主宰之「天」至宋明時期已高度物質化和義理化。自晚明伊始，由於受到東傳之天主教的感染，「天」的蘊含又出現了意志主宰化的傾向。至清初，這個傾向益發得到擴散、蔓延，以致出現了一種與宋明理學不同的「敬天」思潮。本文以許三禮的敬天思想為個案，探討了許氏圍繞「告天」儀式而重新詮釋天人關係的方式及具體內涵。文章指出，許氏從意志主宰之「天」出發，一方面對整個儒家道統做出了重新評估，另一方面又在評估之中形成了一個條貫有序的思想系統。文章在梳理許氏思想脈絡的基礎上，深入探討了告天儀式的經典選擇及其原因、告天思想的接承與流播狀況。

The thought and the ritual of Tian-worship came into being in ancient times, but the connotation of Tian has changed much. Put briefly, Tian as a god had been changed into one as a natural law to the extent that most neo-Confucianists had accepted in the Song and Ming Dynasties. Owing to the influence of Roman Catholic scholars, however, the meaning of Tian as a god reappeared in the late Ming Dynasty, while in the early Qing Dynasty that understanding even became a widespread trend of thought quite different from neo-Confucianism. Taking Xu Sanli as a case in point and focusing on the ritual of his Tian-worship, the article probes into the way by which he re- interprets traditional ideas on the relation between Tian and human being, and thereafter analyses its concrete contents.