Tao-sheng’s connection with the T’ien-t’ai School can be viewed in terms of, among others, the two scriptures, the Nirvāṇa Sūtra and the Lotus Sūtra. It may be suggested that the importance placed on them by Tao-sheng prior to any other masters was faithfully relayed to the T’ien-t’ai tradition. The two scriptures are lumped together in the T’ien-t’ai schema of classification of teachings (p’an-chiao): in the category of the Five Periods the Nirvāṇa and the Lotus belong to the ‘final’ period. There is a subtle distinction between the two, of course: for the T’ien-t’ai School, the Lotus represents the ultimate (“round”) doctrine of the Buddha’s teaching career; whereas the Nirvāṇa, taught simultaneously, represents a résumé of all other teachings expounded before, thereby taking a somewhat penultimate position, supplementary and subsidiary to the Lotus.

In addition to his exegesis of the scriptures, Tao-sheng contributed to the development of the T’ien-t’ai School in two other ways. First, he is credited with the invention of one of the two earliest prototypes of the p’an-chiao system itself. In the [Commentary on the Lotus Sūtra], Tao-sheng puts forward a scheme of four Dharma wheels, representing the Buddha’s teaching career: the good-and-pure, the expedient, the true, and the residueless. Although Tao-sheng does not explicitly match any of the sūtras with these stages, the last two seem to suggest the Lotus and the Nirvāṇa, in that order. Being the case, this is in contrast with the p’an chiao system of the T’ien-t’ai, in which, as said before, the two sūtras are both classified as of the final period, with the Lotus accorded the more significant role. Yet, the T’ien-t’ai schema, along with a similar schema in the Hua-yen school, represents an upshot of the development started by Tao-sheng.

The second way Tao-sheng contributed to the development of
T’ien-t’ai has to do with its Eight Doctrines, consisting of one set of four “transforming methods” and a set of four doctrines. The first two, gradual and sudden teachings, probably had their origin in Tao-sheng’s theory of enlightenment, as did the later tendency to view the problem of sudden versus gradual syncretically, whereby the two were accommodated without contradiction. The germ of this perspective can be seen even in Tao-sheng and his gradualist opponent and contemporary, Hui-kuan. Gradualism can be found throughout Tao-sheng’s commentary—his division of the Buddha’s teachings itself implies nothing less than a gradual learning process. Similarly, behind Hui-kuan’s theory is a clear tolerance toward Tao-sheng’s theory. Hui-kuan in fact came up with a p’an-chiao scheme a little closer to the T’ien-t’ai and Hua-yen models than Tao-sheng’s. The two main branches of Hui-kuan’s scheme are “gradual teaching” and “sudden teaching.” Sudden refers to the Huayen Sūtra whereas gradual encompasses other sūtras and doctrines, including the Nirvāṇa and Lotus.

There are still other points of connection. For example, Tao-sheng speaks of “to converge and return” (hui-kuei) with implicit reference to the theme of the Lotus Sūtra that the three vehicles as provisional devices give way to the One Vehicle as the true goal. Tao-sheng interprets this as a dialectical process, with an overtone of “returning,” a notion harking back to the Taoist idea of “returning to the origin” (fan-pen). In T’ien-t’ai, it is paraphrased as “the three being converged to return to the One” (or “unity of three in One”) (hui-san kuei-i). The description of the “three” as “provisional” (ch’ūan) and the “One” as real (shih), encapsulated in the T’ien-t’ai phrase, “to lay the exigency [of three] open and manifest the real” (k’ai-ch’ūan hsien-shih) was originally coined by Tao-sheng. Tao-sheng is cited frequently by Chih-i (538-597), the actual systematizer of the school, throughout his various commentaries on the Lotus.