本文旨在探討第五世紀初長安僧團在佛教思想上的轉變，此處所謂的長安僧團仍是指鴆摩羅什來華後，幫忙他譯經以及聽經聞法的弟子而言。這些人在羅什來華之前，大都已有良好的佛學根柢，對於般若思想也有格義式的了解，後來因為羅什的介紹下而能正確的理解般若思想，但從格義到正確的了解，中國人事實上經過了一、二百年的等待，為何羅什去世後的四、五年間立刻從中觀的空宗，走入「大乘有宗」的佛性世界，其中一個原因當然是因為《泥洹經》的傳入，但筆者認為這只是引起變化的表象，真正的原因當起自僧團內部，所以筆者試以羅什最重要的弟子之一－僧叡做為探討對象，希望能對此一現象提出一個說明。 為了要探究這個轉變的軌跡，筆者必須先行了解僧叡這位關鍵性的人物，釐清他與慧叡之間的關係，並確定〈喻疑〉一文的作者。其次，透過僧叡對《般若經》及《法華經》的態度，來理解中觀察宗及佛性有宗在他心中地位的轉變，此部分大抵可以分為三個階段來分析，在第一階段中僧叡是以「般若納法華」的，也就是援引《般若經》中的觀點來看待《法華經》中有關佛陀實體的部分。到了第二個階段，僧叡規視「般若與法華為各自獨立」的經典，最後一個階段是指僧叡接觸到《大般涅槃經》之後，此時的僧叡對《般若經》的態度只保存了它袪除虛妄的作用，但在虛妄盡除之後，他卻認為還存在著一個法身的實體。這三個階段可以視為僧叡漸次離開般若，而逐漸走向佛性有宗歷程，同時也可以作為早期中國佛教由「空」入「有」轉變的軌跡之一。

　　　　　This paper discusses why and how the Ch'ang-an Buddhist sangha changed their emphasis from the Buddihist concept of emptiness ("k'ung," sunyata) to that of existence ("yu," being). Founded and led by Kumarajlra (344-143), the sangha advocated using the concept of emptiness to understand the Buddha and his teachings. The sangha, however, stared propagating the concept of existence after Kumarajlra died. The shift can be traced from some of the key figures in the sangha and their intellectual journeys, and Seng-jui, one of the most important disciples of Kumarajlra, can be used as an example to illustrate his point. The first section of the article delineates the relationship between Seng-jui and Hui-jui. I argue that Seng-jui and not Hui-jui wrote "Yu-I" (喻疑), one of the most important texts that clearly demonstrates the change in Buddhist philosophical thought in early fifth century China. In the second section, I maintain that Seng-jui's change in thought underwent three stages. At first, Seng-jui added the Saddharma-pundarika sutra (Fa-hua ching 法華經) to the Prajna (Po-je ching 般若經). Later on, he approached these two sutras and their philosophical thoughts separately. In the end, he espoused his new concept, "Saddharma-pundarlka for foundation, Prajna for practical application" (Po-je wei yung, Fa-hua wei shih 般若為用，法華為實). By changing his philosophy, Seng-jui left Kumarajlra's emphasis on emptiness to develop his own way of understanding the Buddha and his teachings. With his espousing of the concept of existence, Seng-jui's new way of thinking can be used to examine the overall shift in Buddhist philosophical thought during early fifth century China.