If what Grand Masters T’ien-t’ai and Dengyō said upon transmitting their teaching is true, we can see that the most essential teaching transmitted from Grand Master T’ien-t’ai is (not the threefold contemplation in a single thought but) the word of the Wonderful Dharma. The threefold contemplation in a single thought is merely a way of practice to attain the Wonderful Dharma. It is the practice as the cause and the Wonderful Dharma is the realm of enlightenment as the result. However, since the practice as the cause includes the result, and the enlightenment as the result includes the cause, the cause and the result are one and inseparable. Contemplating on the Wonderful Dharma, which includes both the cause and result, a person can attain the merit of acquiring the Wonderful Principle of all (Buddhist) teachings (as mentioned in their transmission documents.)
Thus, we should know that it is indeed a prejudice to insist on such a fallacy saying, “The ultimate teaching of Grand Master T’ien-t’ai establishes a teaching of the ‘concentration and insight of no thought’ other than the distinction between the theoretical and essential sections, and this ‘concentration and insight of no thought’ is beyond description and thus the most important secret teaching.” Great Bodhisattvas such as those called Four Reliances respectfully interpreted the sūtras expounded by the Buddha and developed their theories. Why should Grand Master T’ien-t’ai alone have established the “concentration and insight of no thought” against the thought of the Buddha? If this “concentration and insight” is not based on the Lotus Sūtra, the Great Concentration and Insight of Grand Master T’ien-t’ai is the same as the (false) teaching of a heavenly devil teaching transmitted from heart to heart, without scriptures or preachings. The Great Concentration and Insight by Grand Master T’ien-t’ai is never such a teaching. It is really regrettable (that many people interpret the teaching incorrectly).
Risshō Kanjō, A Treatise on Establishing the Right Way of Meditation, Writings of Nichiren Shōnin, Doctrine 2, Page 230