Śrāvakas and Pratyekabuddhas Do Not See the Emptiness of Ultimate Truth (paramārtha-śūnyatā)

Original text of the Mahāparinirvāṇa Sūtra: 中道者名为佛性。以是义故。佛性常恒。无有变异。无明覆故。令诸众生。不能得见。声闻缘觉见一切空。不见不空。乃至见一切无我。不见于我。以是义故。不得第一义空。不得第一义空故。不行中道。无中道故。不见佛性。

Explanation: The Middle Way is called the Buddha-nature; therefore it is said that the Buddha-nature is constant and permanent, without change or variation. Because ignorance covers the mind's eye, sentient beings are unable to see the Buddha-nature. The practice of śrāvakas and pratyekabuddhas remains only within the phenomenal realm and cannot transcend beyond the phenomenal realm, so they can only see the emptiness of all dharmas within the phenomenal realm, but cannot see the non-empty Buddha-nature beyond the phenomenal realm. Moreover, śrāvakas and pratyekabuddhas can only see that all dharmas in the phenomenal realm are without self, yet they cannot see the Buddha-nature self beyond the phenomenal realm. Therefore, śrāvakas and pratyekabuddhas cannot realize the emptiness of ultimate meaning (paramārtha). Because they cannot realize the emptiness of ultimate meaning, śrāvakas and pratyekabuddhas are not practicing the Middle Way. Because they lack the Middle Way, they do not see the Buddha-nature, which is the Middle Way.

Regarding the Middle Way nature of the Buddha-nature, one may refer to the Middle Way nature of the tathāgatagarbha taught by the Buddha in the Śūraṅgama Sūtra. Both the tathāgatagarbha and the Buddha-nature are existent dharmas, truly existing; their essence is not empty, while their nature is emptiness. Because of ignorance, sentient beings cling to the phenomenal dharmas of the worldly realm and lack the wisdom to investigate the real and true dharma behind the phenomena, and thus cannot realize the tathāgatagarbha and the Buddha-nature.

Śrāvakas and pratyekabuddhas also have ignorance with respect to the Mahāyāna dharma; they likewise have not investigated the real and true dharma behind the phenomenal realm, and so cannot truly realize the tathāgatagarbha and the Buddha-nature. They only see the emptiness of the phenomenal realm and do not see the non-emptiness of the true dharma behind it. They do not know that it is precisely because of the non-emptiness of the true dharma's ultimate meaning that the emptiness of the phenomenal realm can exist. Therefore, their practice leans toward emptiness and lacks the Middle Way. And that true dharma is precisely the essence of sentient beings, their original face—that is, the self of sentient beings, the true self. From the true self is derived the false self of the five aggregates and the worldly realm, yet the false self is not the self. Therefore, the emptiness realized by śrāvakas and pratyekabuddhas is not ultimate, and thus is not the Middle Way; it is deviated, leaning toward pure emptiness, unable to achieve the perfect harmony of emptiness and existence.