佛性觀念是在南北朝初年(五世紀初葉)， 隨著以佛性為中心主題的大乘〈涅槃經〉譯出，開始受到注意，並且迅速成為普受關注的理論課題，對中國佛教思想的形成和發展，產生深遠影響。由於早期中國佛性論者都是以〈涅槃經〉為其立說的本據，而〈涅槃經〉經常出現「一切眾生實有佛性」、「一切眾生未來之世當有阿耨多羅三說三菩提」一類說話，因此所有眾生同樣具有佛性、一樣可以證得究極覺悟，乃是早期中國佛性論的通義。由是當唐朝初年(七世紀中葉 )，以玄奘(約 602- 約 664) 、窺基 (632－682) 為首的法相宗興起，提出「五種種性」說法，宣稱有些眾生本來沒有成佛之性，因而永遠不能證得佛果，使即時掀起激烈爭論。在當時眾多持反對立場的論者中，以法寶 (約 627- 約 705) 最為著名。法寶為玄獎的門生， 然而他深受如來藏思想影響，對師門教學每採取批判態度。在佛性問題上，法寶承襲早期中國佛性論以如來藏學說詮釋佛性學說的習尚，並且以發揚〈涅槃經〉一切眾生皆得成佛教說為己任，從而對玄裝門下盛唱的五種種性和相關觀念，非常不滿，作〈一乘佛性權實論〉和〈一乘佛性究竟諭〉，全面加以破斥。本文根據法寶這兩種論著，對其佛性思想作出全面探討。全文分六節：第一節介紹法寶的生平和著作。第二節概述〈涅槃經〉的佛性教說和法寶以前流行的各種佛性說法，作為下文討論的背景。法寶談論佛性最具創意地方，在於他把佛性論跟判教論結合；通過設立五時判教分類，把法相宗之部分眾生無佛性主張判屬前時的不了義說法，把自家全部眾生皆有佛性主張判屬後時的了義說法，達至抑他揚己的目的。這是本文第三節的主題。第四節析述法寶對〈涅槃經〉與及對當代通行的各種佛性釋義、佛性分類、和跟佛性相關觀念的詮釋，凸顯如來藏思想在法寶的佛性思想中的主導地位。第五節為本文的核心部分，逐一檢視法寶對五種種性說法所包涵各主要理念的批難，其中包括「法爾定性」、「定性二乘」、「一分無性」等；此外還論及法寶對法相宗的「變易生死」 觀、「一闡提」觀、「本有無漏種子」觀念的駁斥。第六章總結全文要點 ， 旁涉法寶對無情存在跟佛性的關係的看法。

　　　　　 Whether all sentient beings possess Buddha-nature, and so can attain Buddhahood, has been a central problem in Mahayana Buddhism in China since its inception; and theoretical interest in this issue deepened from the early fifth century. Generally speaking, early Chinese theories of Buddha-nature were based on the Mahaparinirvana-sutra, which held that all beings possess Buddha-nature and can attain Buddhahood. A major controversy developed over this issue in the mid-seventh century, when Xuanzang (ca. 602-664) and his followers in the Faxiang sect put forward the theory of five lineages, maintaining the existence of three types of sentient beings incapable of realizing Buddhahood due to their lack of Buddha-nature. Among the critics of this theory, the most vocal and versatile was one who had been his former student, but who had also been deeply influenced by tathagatagarbha teachings, Fabao (ca. 627-ca. 705). This paper is a study of Fabao's teachings about the Buddha-nature. It is made up of six sections. Section one provides a succinct account of the life and writings of Fabao. Section two gives a brief outline of the Buddha-nature teachings of the Mahayana Mahaparinirvana-sutra, on which Fabao's teachings about the Buddha-nature are based. Section three comprises a detailed study of Fabao's creative attempt to establish a correlation between various opinions on the subject of lineages and various periods of Buddhist teachings, with a view to relegating Xuanzang's theory of five lineages to an earlier, inferior form of Buddhist teachings. Section four examines various definitions, including Fabao's, of the term "Buddha-nature,'' his analysis of Buddha-nature into different types, and his interpretation of a number of ideas closely connected with the idea of Buddha-nature; it highlights the centrality of the tathagatagarbha doctrine to Fabao's Buddha-nature teachings. Section five analyzes Fabao's critiques of several key notions underlying Xuanzang's theory of five lineages, and surveys Fabao's disparagements of Xuanzang's interpretation of a number of popular Mahayana concepts (such as "existence qua transformation'' and "icchantika'') in his expositions of the theory of five lineages. The paper concludes with a discussion of Fabao's view about the relation between the Buddha-nature and non-sentient objects.