本文探討牟宗三《佛性與般若》一書，對於天台智者「不斷斷」之詮釋。首先論述牟宗三所認為的智顗之原初洞見，接著分析牟宗三對「不斷斷」概念之解讀，最後再對牟宗三之詮解作一檢討與反省。 對於牟宗三所闡釋的「不斷斷」，本文認為此一概念，應是為符合天台圓教義理系統之論述而來，已帶有一定的預設；即智顗應是先有圓教之觀點，再以「不斷斷」之提出，使其成為圓教的要件之一。此外，牟宗三認為「煩惱即菩提」等語句，乃是「不斷斷」之理境，但此理境是否可理解為圓實說，可能有不同的看法，如在其它的大乘經典即指出此為對治之用的隨宜說；而且其中隨宜的對治作用，若理解與運用不當，也易於產生負面之效應。

This paper discusses Mou Zongsan’s interpretation of Tiantai Zhi-yi’s concept of “the Extinction of Un-Extinction” as treated in his book Buddha Nature and Perfection of Wisdom. At the outset, Mou Zongsan’s presentation of Tiantai Zhi-yi’s original insights is introduced and subsequently, his understanding of Zhi-yi’s idea of “the Extinction of Un-Extinction” is analyzed. The paper then concludes with a critical reflection upon Mou Zongsan’s interpretation of “the Extinction of Un-Extinction”. In this paper, I attempt to point out that the concept of “the Extinction of Un-Extinction” is meant to cohere with Tiantai’s theoretical structure of the “Consummate Teaching” and furthermore has its own inherent presupposetion -- it appears as though Zhi-yi gives rise to the viewpoint of consummate teaching first, and thereupon develops his interpretation of “the Extinction of Un-Extinction” as one of the necessary conditions of the “Consummate Teaching.” Discord with Mou Zongsan’s interpretation, this paper also examines the validity of the claim that “Vexation is Bodhi” belongs to the very same theoretical domain as “the Extinction of Un-Extinction.” Doubt is raised over whether sayings such as “Vexation is Bodhi” or “the Extinction of Un-Extinction” could rightfully be considered a “Consummate and Truthful Teaching.” For instance, other Mahayana sutras treat this claim as being merely a kind of “Flexible Measures” intended to cure mental afflictions. Moreover, such a temporary treatment tends to have negative effects if misunderstood or applied inappropriately.