In Zhiyi's explanation of the Three Teachings (the Three Characteristic Teachings in the Lotus Sutra) in "Hokke Gengi" (Essentials of the Lotus Sutra), his second point mentioned the procedure of guiding sentient beings to the other shore of liberation through the Three Stages of Benefit, i.e., geshu yaku, chojuku yaku and gedatsu yaku, spanning sanzen-jin-tengo (an immensely long period of time).
智顗は『法華玄義』1上で、すなわち三種の教相（法華経にある3つの特徴的な教説）を立てる中の2つ目に三千塵点劫にわたる「化道始終不始終相」を述べた。