The Difference Between the Buddha's Nirvāṇa and the Arhat's Nirvāṇa

There is an essential difference between the Buddha's nirvāṇa and the arhat's nirvāṇa. After the Buddha's nirvāṇa, He still manifests countless bodies of the five aggregates throughout the worlds of the ten directions to liberate sentient beings; therefore the Buddha says that the body of the five aggregates is called liberated form (mokṣa-rūpa). When the Buddha's conditions for liberating sentient beings in a particular world have come to an end, He extinguishes the physical body, and this is conventionally called nirvāṇa. For example, when Śākyamuni Buddha entered nirvāṇa in the Sahā world, His physical body temporarily departed and ceased, yet Śākyamuni Buddha remains the Dharma lord, master, and teacher of the Sahā world, and the sentient beings of the Sahā world are still disciples taught and transformed by Śākyamuni Buddha. At the same time, Śākyamuni Buddha manifests immeasurable and boundless bodies of the five aggregates throughout the worlds of the ten directions to teach and liberate sentient beings in all directions. After an arhat enters nirvāṇa, there will no longer be any physical body or five aggregates; therefore, after an arhat's nirvāṇa there is no liberated form, and their nirvāṇa lacks self-mastery (avaśatā)—their liberation is not complete.

The Buddha possesses the five aggregates, yet He is liberated; His liberated form can be seen by sentient beings with the naked eye and is not bound by any dharma of the world. Although sentient beings also possess the five aggregates, they are bound by worldly dharmas and therefore cannot attain liberation. When the mind is liberated (cetovimutti), the physical body is liberated, and the five aggregates are all liberated. Therefore, liberation does not require extinguishing the physical body and the five aggregates; rather, one must extinguish the mind's thoughts and views that are not in accord with reason and the Dharma. When one's thoughts are transformed into views and insights that accord with reason and reality, one is liberated.