What is the Dharma Realm? Where do the Buddhas attain Buddhahood?

Question: What is the dharmadhātu? Where did the Buddhas attain buddhahood?

Answer: The dharmadhātu is divided into the supramundane dharmadhātu and the mundane dharmadhātu. The mundane dharmadhātu is divided into the eighteen dhātus, the ten dharmadhātus, and the three realms of existence. The eighteen dhātus are the six sense faculties, six sense objects, and six consciousnesses of sentient beings; the ten dharmadhātus are the dharmadhātus of the four noble ones and the six ordinary realms. "Dhātu" (界) means function, boundary, and the differentiation of seeds—it is a dividing line. Different dhātus have different functions and operations: the functions of the six sense faculties differ from those of the six sense objects, and also differ from those of the six consciousnesses. The beings of the six realms each have their own boundaries, and the four kinds of noble ones each have their own boundaries; each of the ten dharmadhātus has its own boundary. The three realms are the desire realm, the form realm, and the formless realm; they also have boundaries, and can also be called dharmadhātus, for the three realms each have their own distinctions and boundaries.

The supramundane dharmadhātu is called the one true dharmadhātu (eka-satya-dharmadhātu), which is the tathāgatagarbha of true suchness. He does not belong to the three realms of existence, is not within the three realms, and has no characteristics of the three realms of existence; yet He is also not outside the three realms of existence. All the dharmas of the three realms of existence, as well as the Buddha-lands of the Buddhas of the ten directions, the Lotus Treasury World (Kusumatala-garbha-vyūhâlaṃkāra-lokadhātu-samudra), and the ocean of worlds, all exist within the one true dharmadhātu, and none of them goes beyond the true mind of suchness. When sentient beings cultivate to the stage of wondrous awakening (sugata-mūrdhan), before attaining buddhahood, they must await in the inner court of Tuṣita as a waiting candidate, waiting for the conditions to ripen, and then descend to the human world to attain the Way through the eight manifestations of a Buddha. When the faculties and dispositions of the beings in the human world have ripened, and the season for the wondrously awakened bodhisattva to attain the Way has also arrived, He will descend to the human world and attain the Way through the eight manifestations. Therefore, all Buddhas come to the human world to accomplish the fruit of buddhahood.