K’ai-san Hsien-i (Opening the three and revealing the one) is the function related to the Subtlety of Objects. This is spoken of in terms of the teaching and principle. Chih-i points out that in the Lotus Sūtra, the truth of emptiness held in the three teachings are identified with the Ultimate Truth. The Buddha made it clear that the underlying principle as the Ultimate Truth is embedded in these three teachings, since the ultimate goal of them is to lead beings to attain the One Vehicle of Buddhahood. (Vol. 2, Page 445)

Chu-san Hsien-i (Abiding in the three and revealing the one) is the function related to the Subtlety of Response. Chih-i says that this is spoken of in terms of the relative knowledge of the Buddha, which is applied expediently by the Buddha to transform living beings. The expedient means used (e.g. abiding in the three vehicles) is for the sake of aiding the manifestation of the Supreme Truth (i.e., revealing the one). (Vol. 2, Page 445)

Chu-i Hsien-i (Abiding in the one and revealing the one) is the function related to the Subtlety of the Threefold Track. This is spoken of in terms of the original intention of the Buddha. Chih-i emphasizes that the Buddha’s intention is to apply the ultimate knowledge to transform living beings. Therefore, the Buddha always abides in the One Buddha-vehicle, and expounds this One Vehicle to teach and transform living beings. (Vol. 2, Page 445)

Chu-i Hsien-i (Abiding in the one and revealing the one) is the function related to the Subtlety of the Threefold Track. This is spoken of in terms of the original intention of the Buddha. Chih-i emphasizes that the Buddha’s intention is to apply the ultimate knowledge to transform living beings. Therefore, the Buddha always abides in the One Buddha-vehicle, and expounds this One Vehicle to teach and transform living beings. (Vol. 2, Page 445)

Fei-san Hsien-i (Abandoning the three and revealing the one) is the function related to the Subtlety of Expounding the Dharma. The above-stated first step destroys disciples’ attachment to the three teachings. In Chih-i’s view, the purpose of the previous refutation is to further abandon these three teachings with the revelation of the One Vehicle, in order to prevent beings in the future time from being attached to them once again. This abandonment is associated with the Buddha’s teaching, for without the teaching, the necessity of abandoning the three teachings will not be made clear. (Vol. 2, Page 444-445)

P’o-san Hsien-i (Refuting the three and revealing the one) is the function associated with the Subtlety of Knowledge. Given that the Three Vehicles (Śrāvaka, Pratyekabuddha and Bodhisattva) mistake the three teachings (Tripiṭaka, Common and Separate) that are designed for them as the Ultimate Truth and become attached to these teachings, the Buddha felt that it is necessary to destroy their attachment in order to reveal the knowledge of the Buddha as the One Vehicle. Therefore, by introducing the one ultimate Buddha-vehicle, the Three Vehicles are prevented from being attached to the three teachings. The refutation and the revelation are associated with the function of the Buddha’s knowledge. Without this function, the Relative Truth of the Three Vehicles and the Ultimate Truth of the One Buddha-vehicle will not be known. (Vol. 2, Page 444)

Chih-i relates function with power. Compared with the function of other sūtras, the Lotus Sūtra is regarded by Chih-i to possess the powerful function, which can fulfill the task of leading beings to attain Buddhahood. The function is only considered to be powerful if the sūtra conveys the state of Buddhahood. To be specific, Chih-i argues that all other sūtras do not present the Buddha’s knowledge and wisdom, they do not convey that the Buddha responds to his own Traces, they do not directly demolish and abandon the Two Vehicles (Śrāvaka and pratyekabuddha), and do not clear away disciples’ doubts about the recent material body of the bodhisattva as Śākyamuni Buddha. The Lotus Sūtra, on the contrary, does not concern the knowledge of the Two Vehicles and the knowledge of the bodhisattva, but only reveals the subtle knowledge of the Buddha. It does not reveal the knowledge and the perception of living beings in the nine Dharma-realms, but only the subtle knowledge and insight of the Buddha. Chih-i goes on to say that the Lotus Sūtra directly demolishes and abandons the effect of the Two Vehicles by employing a parable of the conjured city (Hua-ch’eng). Like the conjured city that should be abandoned, the practice of the Two Vehicles as the cause should be abandoned too. In the Lotus Sūtra, all types of the expedient teaching are considered to be the Relative Truth in the Traces, and the place of the Origin is revealed as containing real merits and virtues, and represents the Ultimate Truth. (Vol. 2, Page 443-444)

Chih-i distinguishes different kinds of cause and effect in terms of four phases: gradual and perfect, perfect and gradual, gradual and gradual, and perfect and perfect.

1. Respecting Gradual and Perfect (Chien-yüan), it is referred by Chih-i to one’s gradual entry to the perfect cause through different methods of practice. Therefore, the cause and effect in this phase is called Gradual and Perfect.
2. Respecting Perfect and Gradual (Yüan-chien), it means that the first and the last stages of practice are perfect, but in the middle stage of practice, one progresses gradually through various positions. Therefore, the cause and effect in this phase is called Perfect and Gradual.
3. Respecting Gradual and Gradual (Chien-chien), it means that one progresses in practice from the Position of the Ten Dwellings all the way up to the Position of the Preliminary Enlightenment. Therefore, the cause and effect in this phase is called Gradual and Gradual.
4. Respecting Perfect and Perfect (Yüan-yüan), it means that the perfect truth that is perfect at the beginning stage as the cause of Buddhahood is attained at the final stage of Subtle Enlightenment as the effect of Buddhahood. Therefore, the cause and effect in this phase is called Perfect and Perfect.

Chih-i asserts that these four phases represent a progress in religious practice expounded in the Lotus Sūtra, starting from the initial phase Gradual and Perfect, and ending with the final phase Perfect and Perfect. (Vol. 2, Page 441)

Chih-i summarizes different types of cause and effect as an indication of one’s religious progress of attaining the Ultimate Truth. This is to first examine various levels of practice in terms of the cause and effect, which are distinguished as either cause or effect. According to Chih-i, the Ten Dwellings are the cause in relation to the Ten Practices, and the Ten Practices are the effect. The Ten Practices are the cause in relation to the Ten Merit-transferences, and the Ten Merit-transferences are the effect. The Ten Merit-transferences are the cause in relation to the Ten Stages, and the Ten Stages are the effect. The Ten Stages are the cause in relation to the Stage of Preliminary Enlightenment, and the Stage of Preliminary Enlightenment is the effect. The Stage of Preliminary Enlightenment is the cause in relation to the Stage of Subtle Enlightenment, and the Stage of Subtle Enlightenment is the effect. (Vol. 2, Page 440-441)

Chih-i emphasizes the superiority of the cause and effect that is stated in the Lotus Sūtra compared with that stated in other sūtras. The coarse or subtle gist is determined in terms of whether or not all Śrāvakas and bodhisattvas can enter one perfect cause of Buddhahood, and simultaneously attain realization as the ultimate effect of Buddhahood. The Lotus Sūtra is considered by Chih-i as subtle, since its cause is perfect and its effect is ultimate, which contains no expedience. Nevertheless, in view of all coarse or subtle causes and effects that can lead one to attain Buddhahood, all of them are subtle. The realization of such an absolute subtlety is through opening the coarseness and revealing the subtlety, by which all the coarse causes and effects in other sūtras are dissolved, and become subtle. (Vol. 2, Page 440)