Is supposition “Reality goes after believing and unreality goes after unbelieving” the law for us to face whichever phenomena in the world? What is the immanence of believing? How does believing act? By studying the operation mechanism of believing, the reality of the truth can be realized and the meaning of the reality of the philosophic “subject” and “object” can be understood. Furthermore, it can be inferred that everything in the world ranging from philosophy, science to religion cannot escape from the constraint of this supposition. Only in Buddhism is there one thing that cannot be named can free from this supposition.