一般以為天台與華嚴之間的差異為，存有論上實相論與唯心論之爭，或者 以為是觀心實踐法門之妄心觀與真心觀之爭。此一印象是由唐代湛然所形成， 又為宋代山家派的天台學者的論述所強化。但這個印象是一種過於簡化天台與 華嚴關係，而為了強調天台特色的說法。 事實上，天台與華嚴皆重視「心」的重要性，天台強調一念三千的觀心法 門，華嚴也有一心法界的理論，二者的形式相似，也都深受《華嚴經》唯心思 想的啟發。到了唐代，透過《大乘起信論》的詮釋，二宗在思想上有更密切的 交互影響。 湛然同意心與法界的圓融思想，但他認為法藏錯解了《大乘起信論》的 「一心」之義涵為，存有論義的超越的真如心。他同意一普遍的心性說，對佛 教觀心實踐義之成立具有必要性，但不同意存有論義的真如心作為一普遍的基 礎。因此替代法藏詮釋《大乘起信論》的「真如不變隨緣」說，但代之以《大 般涅槃經》的佛性思想，而言「佛性隨緣」，因為佛性就是，現實或善或惡眾 生，實際上普遍可以成佛的可能性，並不像真如心僅為是為一超越的理想的概念，故湛然認為佛性才能真正徹底實現由實踐義到存有義上的圓融。可是湛然 的詮釋，對華嚴宗而言並不公平，因為他忽略了華嚴宗真心思想的另一個理解 的可能。 本文的目的，不是為了會通天台與華嚴，而在於跳脫宗派意識，立足於心 性哲學思想的開展脈絡來討論二宗思想交涉問題；同時也顯示，在《華嚴經》 及《大乘起信論》文獻上的詮釋關鍵，是二宗思想產生同質及歧異的理由。

It is generally held that the major differences between Tiantai and Huayan Buddhism were those between their respective arguments for “realism” (實相論) and “idealism” (唯心論) and between their empirical arguments for the delusory mind (妄心) and pure mind (真心) regarding the contemplative method. This article argues that such view oversimplifies both Tiantai and Huayan’s teachings. It further shows that this view was proposed by the Tiantai patriarch Jingxi Zhanran (711-782), and then amplified by the “mountain” (山家) branch of the Tiantai school in the Song dynasty. This view, in favor of the Tiantai school, is a misrepresentation of the relationship between the two schools of thought. In my view, both Tiantai and Huayan emphasize the importance of mind: in Tiantai doctrine, one instance of mind embraces three thousands worlds (一念三 千), and in Huayan, the entire dharma-realm is embedded in one mind (一心法界). These doctrines are similar in format and were originated from Huayan’s idealism. During the Tang dynasty, mutual doctrinal influences between the two schools increased in the process of interpreting the Dasheng qixinlun. Zhanran agrees with the oneness of the dharma realm and mind, but rejects Xianshou Fazang’s (643-712) interpretation of the “one mind” in the Dasheng qixin lun as transcendent true mind in ontological sense. Zhanran agrees that a general theory of true mind is necessary for the establishment of the practice of mind contemplation, but he disapproves an ontologically true mind as a universal theoretical basis. In replacement of Fazang’s understanding of the Qixin lun that “the unconditioned suchness-mind conditions all phenomena,” Zhanran teaches a theory that “all phenomena are conditioned by Buddha-nature” based on the Nirvana Sutra. For Zhanran, the Buddha-nature means the potentiality of attaining Buddhahood endowed by all sentient beings of good and evil. Unlike the “suchness-mind,” Buddha-nature is not merely a transcendent ideal. Therefore, Zhanran claims that only this theory of Buddha-nature can actually realize perfection of both practice and ontology. In my view, however, Zhanran’s interpretation is an incomplete understanding of Hyayan Buddhism, because he seems to overlook the other possible interpretation of Huayan’s “true suchnessmind.” This paper does not intend to understanding with Tiantai and Huayan Buddhism, rather, it intends a non-sectarian understanding of the debates between the two schools about the nature of the mind. It tries to show that the debates were the result of differences in the interpretation by the two schools of several key concepts found in the Dasheng qixin lun and Huayan jing.