[T]he Buddhist world in South and North China during fifth and six centuries was divided by its focus on either the doctrinal aspect or practical aspect. Chih-i’s elaboration of the first three Subtleties (Objects, Knowledge and Practice) resolves the discrepancy between Southern and Northern branches by laying equal importance of both doctrinal and practical aspects.

1. The Subtlety of Objects emphasizes the importance of the doctrinal aspect concerning truth. Without truth, liberation is not possible, since one’s attainment of liberation is based on one’s realization of truth.
2. The Subtlety of Knowledge connects these aspects with each other. On the one hand, because of knowledge, one is able to penetrate the doctrine of truth. On the other hand, from Chih-i’s elaboration of knowledge (as we see how the twenty kinds of knowledge are derived from various types of practice),29 knowledge is obviously related to the practical aspect: without practice, knowledge cannot be obtained.
3. The Subtlety of Practice emphasizes the significance of the practical aspect in obtaining knowledge and penetrating truth. Therefore, these three subtleties embrace all aspects of Buddhism, for all aspects of Buddhism are concerned with doctrine and practice. (Vol. 2, Page 465)