In chapter 6, “Assurance of Becoming a Buddha,” the Buddha reassures the four great disciples (the shravakas of chapter 5) and five hundred other disciples that they will become buddhas in the future. The basis of this assurance is given in chapter 7. Here we find the parable of the treasure and the fantastic (or temporary) castle-city. The way to the truth is steep; people become discouraged along the way. Then the Buddha provides a temporary truth (the three vehicles) according to the ability of people and lets them rest there. When they are rested, the Buddha encourages them to pursue ultimate truth (the one vehicle).

This is the truth taught in the parable of the fantastic castle-city. Temporary truth is likened to a castle-city, and ultimate truth to a great treasure. The four noble truths are taught to shravakas as temporary truths, the law of twelve causes to pratyekabuddhas, and the practice of the six transcendental practices (paramitas) to bodhisattvas. Finally, they are all led to and awakened by the one vehicle—that is, by ultimate truth.

This “opening, showing, becoming enlightened, and entering” is also in chapter 2. Tiantai Zhiyi thought very highly of these words and theorized about them in several ways. Many Buddhist sects very highly respect the following words from chapter 7 as a vow, and chant them in Buddhist services.

May these blessings
Extend to all,
That we with all the living
Together attain the Buddha way.