What Is Dharmadhatu? Where Do All Buddhas Attain Buddhahood?

Question: What is the Dharmadhātu? Where do all Buddhas attain Buddhahood?

Answer: The Dharmadhātu is divided into the supramundane Dharmadhātu and the mundane Dharmadhātu. The mundane Dharmadhātu consists of the eighteen realms, the ten Dharmadhātus, and the three realms of existence. The eighteen realms refer to the six sense faculties, six sense objects, and six consciousnesses of sentient beings. The ten Dharmadhātus encompass the four holy realms and the six mundane realms. "Realm" (dhātu) denotes function, boundary, distinction of seeds—it is a dividing line. Different realms possess distinct functions and roles: the functions of the six sense faculties differ from those of the six sense objects, and both differ from the functions of the six consciousnesses. Beings in the six destinies each have their own boundaries; the four types of noble ones each have their own boundaries; the ten Dharmadhātus each have their own boundaries. The three realms—the desire realm, form realm, and formless realm—also have boundaries and may be called Dharmadhātus, each possessing its own distinctions.

The supramundane Dharmadhātu is called the One True Dharmadhātu, which is the true suchness, the tathāgatagarbha. It does not belong to the three realms of existence, does not reside within the three realms, and lacks the characteristics of the three realms, yet it is not separate from the three realms. All phenomena of the three realms, as well as the Buddha-lands of the ten directions, the Flower Store World, and the ocean of worlds, are all within the One True Dharmadhātu—none exist outside the true suchness mind. Before sentient beings cultivate to the stage of Wonderful Enlightenment and attain Buddhahood, they must await in the Inner Court of Tuṣita for the conditions to mature, preparing to descend into the human realm and manifest the eight aspects of a Buddha's life to attain the Way. When the faculties of human beings ripen and the time for the Bodhisattva of Wonderful Enlightenment to attain the Way arrives, they must descend into the human realm to manifest the eight aspects and realize the Way. Therefore, all Buddhas come to the human realm to accomplish the Buddha-fruit.