本文旨在比較海德格哲學與天台哲學。在海德格哲學中，「共屬」表達人與存有之關係；在天台哲學中，「即」則用以連接兩造內在矛盾的語詞，以表達一種弔詭的情境。本文試圖透過「共屬」與「即」的對比研究，顯示兩門哲學在本質上的相似性，並嘗試澄清其詭譎的表達形式。 在行文上，本文包括兩個部分。於第一部分，我們比較共屬的相互轉讓與「即」的詭譎形式。為了理解此一詭譎的形式，海德格要求我們跳離傳統的形上學思維，「退回」根源的思維。在文章的第二部分，本文將試圖澄清海德格「退回」之意義，並將其對比於天台宗之「不斷斷」。

　　　　　 In this article, I try to compare Heidegger's philosophy with T'ien-t'ai Buddhism. In Heidegger's philosophy, the concept of “belonging together” is used to thematize the relation between human being and Being. In T'ien-t'ai philosophy, the concept of “chi” is used to connect two internally contradictory terms to express a paradoxical situation. Through a comparative study of these two concepts, I attempt to show some essential similarities between these two philosophies, and to clarify their paradoxical forms of articulation. This paper includes two parts. Part one deals with a comparative study of the mutual reciprocity of “belonging together” and the paradoxical form of “chi.” In order to understand this paradoxical form of articulation, Heidegger urges us to “step back” (Schritt zuruck) from traditional metaphysics and go into the origin of metaphysics. Then I will try, in part two, to clarify the meaning of this concept of “stepping back” and to compare it with the concept of “pu-tuan-tuan” of T'ien-t'ai Buddhism.