以玄奘（約602-約664）、窺基(632-682)爲首的法相宗，在唐期初年（七世紀中葉）提出「五種種性」說法，宣稱有「決定聲聞種性」、「決定緣覺種性」、「無種性」三類眾生，他們由於本來沒有成佛之性，從而永遠不能證得佛果；在一向相信一切眾生皆具佛性、同樣可以成佛的中國佛教界，引起巨大迴響，反對之聲此起彼落。反對者中聲望最隆者爲法寶（約627-705），他撰作《一乘佛性究竟論》，對五種種性和其相關觀念，全面加以破斥。法寶的批評引起了窺基高弟慧沼(648-714)的強烈不滿，寫成《能顯中邊慧日論》，爲師門的觀點大力申辯。法寶的批難和慧沼的反詰，把唐代由五種種性說法出現所引起的佛性論爭，推展至高舉。本人曾在本刊第二十二期（2003年3月）發表〈法寶的佛性思想〉一文，申介法寶的佛性教說。本文探討其反對者慧沼一方的論說，析述慧沼如何引入「定性」和「不定性」、「理性」和「行性」等界別，對作爲法寶佛性教說基礎的「五教」判教體系和「理心」觀念，作出破斥；又申示慧沼如何借助「性」、「習」兩種種性、「理性全分，行性少分」等說法，爲作爲法相宗佛性觀核心的「法爾性別」、「變易生死即是增壽」、「一闈提畢竟無涅架性」箏觀念，作出辯解；最後試圖通過凸顯法寶、慧沼兩者的佛性思想進路之殊異，展示唐代這場著名佛性論爭分波癥結之所在。

In the early Tang period (seventh century), the debate over whether all sentient beings can attain Buddhahood, centering on the doctrine of five lineages of the Faxiang School, is an important episode in the development of the philosophy of Buddha-nature in China. The debate came to a head when Fabao (c. 627-c. 705) launched a frontal attack on the Faxiang position in his Yicheng foxing jiujing lun. Huizhao (648-714), a leading Faxiang theorist, rose to defend Faxiang's doctrine with a point-by-point rebuttal of Fabao's criticisms. Huizhao's book, Nengxian zhongbian huiri lun, became a key to the understanding of both Huizhao and the Faxiang school's thought on the matter. In my paper "Fabao's Teachings about Buddha-Nature" (published in vol. 22 of this journal), I have examined Fabao's position. In the present paper, I will present the arguments on Huizhao's side of the case. It demonstrates how Huizhao refutes the ideas of "five teachings" and "true mind" central to Fabao's Buddha-nature teaching by resorting to the distinctions between "determinate" and "indeterminate" lineage, and between Buddha-nature "as principle" and "as practice." It shows how Huizhao defends the key ideas of the Faxiang Buddha-nature teaching, such as the idea of the icchantika being totally devoid of the nature of nirvana, by bringing in the distinction between "inborn" and "produced" nature, and by upholding the partial presence of "Buddha-nature as practice" in contrast with the universal presence of "Buddha-nature as principle." By highlighting the difference in Fabao and Huizhao's approaches to the Buddha-nature problem, this paper attempts to reveal the crux of the Buddha-nature debate, which had as its participants some of the most prominent early Tang Buddhist thinkers.