The main source of the concept of "one mind" as taught in Tiantai philosophy is the "Treatise on the Awakening of Faith in the Mahayana". This scripture teaches the concept of "the two gates of the one mind": the "one mind" comprises the two qualities of purity and impurity. The Tiantai-masters Huisi (515-577), Zhiyi (538-597), Zhanran (711-782), and Zhili (960-1028) all accepted and further developed this concept of the "Awakening of Faith in the Mahayana". Concerning the problem of the relationship true/false, this paper explains that these four masters taught that true and false actually are united. As to the problem of form/mind, they all held that "all dharmas are completely inherent to the mind," but Zhili even further proposed a concept of the "complete inherence to the dharmas." With respect to ontological positions, the paper explains that the four masters considered the "one mind" to be the highest essence of all dharmas. Concerning religious practice, they all took the "one mind" as an object of meditation and practice. All of these problems are central issues of Tiantai philosophy. The Tiantai-masters constructed the system of Tiantai philosophy in response to these issues. The essence of Tiantai philosophy is the teaching of "the whole universe in one thought" and "the comlete inherence in both form and mind.
