曹洞宗的五位思想和天臺宗所論的三諦都表達了東亞佛教對宗教究極真理的特殊理解，表現了中國古典哲學的「三」的共通思想模型，此一共通的思想模式可被命名為「三法圓融」的思想模式，由三到五的過程體現了中國佛教在發展的過程中的關於宗教究極真理（ultimate truth）的全體性和主動性的進一步理解。本論文闡釋東亞佛教關於宗教的究極真理的理解，闡明其共通的三法圓融的思想結構，論述由二諦說進展至三諦說、由龍樹中觀學進展至三法圓融的天臺圓教的理論根據和觀點轉移。本論文對天臺智顗的三諦說的三法不縱不橫與不三不一的基本結構亦加以闡明，並闡釋曹洞五位的「五」的思想蘊含了什麼樣的關於三法圓融的東亞圓教的進一步的發展，吾人並對與此相關的曹洞五位的迴互思想略加闡述。

　　　　　This article tackles the question of T'ien-tai's theory of three truth and Ts'ao-tung's throry of five positions, that are regarded as the research of the ultimate reality. Ts'ao-tung's throry of five positions presents the dialectical absoluteness of the dynamic ultimate reality. An analysis of the model of the “three-one” in T'ien-tai-buddhism and its development in the Ts'ao-tung's throry of five positions is presented and discussed here.