The Essence of the Three Gates in Zen

The Three Gates of Zen are thresholds for the advancement of wisdom. Passing the first gate verifies the Tathāgatagarbha. Passing the second gate allows one to perceive the nature of the Tathāgatagarbha, which is the Buddha-nature, and to recognize the functioning of the Tathāgatagarbha within all six sense objects. The third gate is the firm barrier; transcending this gate resolves the great matter of birth and death, granting the capacity to enter Nirvāṇa. Upon completing Zen meditation practice, one must then proceed to study the comprehensive teachings of Vijñapti-mātratā (Consciousness-Only).

Realization in Zen is equivalent to the initial fruit (Srotāpanna) in the Hinayana path. The third gate corresponds to the third and fourth fruits (Sakṛdāgāmin and Anāgāmin, or Arhat) in the Hinayana. Attaining the Mahayana fruit simultaneously obtains the Hinayana fruit, whereas achieving the Hinayana fruit does not necessarily entail the Mahayana fruit, indicating that Mahayana encompasses Hinayana. When Arhats perceive emptiness, they perceive the emptiness of the self (pudgala-śūnyatā), knowing that the five aggregates and eighteen elements are empty and are not the true self; they have not yet realized the Tathāgatagarbha. When Bodhisattvas perceive emptiness, they realize that the Tathāgatagarbha is real—it is the mind of emptiness (śūnyatā-citta)—while simultaneously knowing that the five aggregates and eighteen elements produced by the Tathāgatagarbha are empty. Both realize emptiness, but the content of their realization is not identical.