The Buddha in the Chinese book "Hokkekyo Convenience Goods" said: "Since I became a Buddha, all kinds of karma, metaphors, extensive preaching and countless conveniences have led all beings to leave their positions." There are many convenient explanations, such as "rationality is the best way, and writing is skillful and convenient"; "All sentient beings are bound in a square, and it is convenient to adapt to the law." Convenience is the road to truth. For example, Tang Bai Juyi's poem "Flowers in the Monk's Courtyard" said: "Looking closely is the poem" Huayan ",which is convenient for the wind to bloom wisdom." Later, it generally refers to opportunity and convenience. For example, Tang Hanwo's poem "Occasionally" said: "Little red notes hate words, which is convenient for slaves to send to Qing Qing." Tiantai Sect believes that the essence of Hokkekyo is "the right to reveal the truth". Master Sui wise man said: "Open the door of convenience and reveal the truth." ("Beijing Wen Sentence" Volume III) Any good statement is also called "prescribing a convenient door". "Jingdezhen Deng Chuan Lu" Volume 21: "The sea is full of clouds, so please open the door." Later, by providing opportunities and convenience, it was called "opening the door to convenience". For example, Wei Ming-Minfeng's "The Monk's Offender" is the fourth fold: "Whoever wants to patrol the Lord and let me go back to the customs will become a spouse."