What we can determine from Chih-i ‘s interpretation of the Lotus Sūtra in the Hsüan-i is that his interpretation is his approach to establish his system of understanding Buddhism, which reflects his perfect harmonization philosophy. Based on his perfect harmonization philosophy, Chih-i manages to comprehensively and coherently portray various theories of different Buddhist schools so that all divisions, aspects, learnings, and theories of Buddhism that appear to be incoherent come to terms with each other as a whole. This is reflected in Chih-i’s presentation of the Buddha’s teaching in which two divisions of Buddhism, the Śrāvakayāna and Mahāyāna, are complimentary to each other rather than contradictory to each other. According to Chih-i, the Buddha’s teaching centers on enlightenment for oneself and for others. Enlightenment for oneself can be generally considered as the goal of Śrāvakayāna Buddhism, and enlightening others as the goal of Mahāyāna Buddhism. As these two divisions appeared to be disconnected before Chih-i ‘s time, they have been unified as a whole in Chih-i’s theory.

The unification of Śrāvakayāna and Mahāyāna is based on Chih-i’s theory of the essential teaching of the Buddha, concerning the cause and effect of Buddhahood. The cause of Buddhahood refers to the Buddha’s practice to attain enlightenment for himself and is embodied by Śrāvakayāna Buddhism; and the effect of Buddhahood refers to the Buddha’s enlightenment that results in his teaching and transformation of sentient beings in order to enlighten them and is embodied by Mahāyāna Buddhism. With this theory of the cause and effect of Buddhahood, the differences between these two divisions of Buddhism are resolved, as each of them represents one aspect of Buddhahood. Since the cause and effect of Buddhahood is the vital force that unifies different aspects of Buddhism, this essential teaching is what underlies Chih-i’s system of understanding Buddhism, and is laid out in the Fa-hua Hsüan-i. (Vol. 2, Page 462)