According to the Mahayana Mahaparinirvana Mahā-sūtra (also called the Nirvana Sutra), the Buddha taught that parinirvana is the realm of the Eternal, Bliss, the Self, and the Pure. Dr Paul Williams states that it refers to the Buddha using the term "Self" in order to win over non-Buddhist ascetics. However, the Mahaparinirvana Sutra is a long and highly composite Mahayana scripture, and the part of the sutra upon which Williams is basing his statement is a portion of the Nirvana Sutra of secondary Central Asian provenance - other parts of the sutra were written in India.
Guang Xing speaks of how the Mahayanists of the Nirvana Sutra understand the mahaparinirvana to be the liberated Self of the eternal Buddha: ‘One of the main themes of the MMPS [Mahayana Mahaparinirvana Sutra] is that the Buddha is eternal … The Mahayanists assert the eternity of the Buddha in two ways in the MMPS. They state that the Buddha is the dharmakaya, and hence eternal. Next, they reinterpret the liberation of the Buddha as mahaparinirvana possessing four attributes: eternity, happiness, self and purity.’ Only in Mahaparinirvana is this True Self held to be fully discernible and accessible.
Many Mahayana Buddhists do not take statements of this kind literally.
Kosho Yamamoto cites a passage in which the Buddha admonishes his monks ('bhiksus') not to dwell inordinately on the idea of the non-Self but to meditate on the Self. Dr. Yamamoto writes:
‘Having dwelt upon the nature of nirvana, the Buddha now explains its positive aspect and says that nirvana has the four attributes of the Eternal, Bliss, the Self, and the Pure … the Buddha says: “O you bhiksus [monks]! Do not abide in the thought of the non-eternal, sorrow, non-Self, and the not-pure and have things as in the case of those people who take the stones, wooden pieces and gravel for the true gem [of the true Dharma] … In every situation, constantly meditate upon the idea of the Self, the idea of the Eternal, Bliss, and the Pure ... Those who, desirous of attaining Reality meditatatively cultivate these ideas, namely, the ideas of the Self [atman], the Eternal, Bliss, and the Pure, will skilfully bring forth the jewel, just like the wise person.” '
Michael Zimmermann, in his study of the Tathagatagarbha Sutra, reveals that not only the Mahaparinirvana Sutra but also the Tathagatagarbha Sutra and the Lankavatara Sutra speak affirmatively of the Self. Zimmermann observes:
the existence of an eternal, imperishable self, that is, buddhahood, is definitely the basic point of the TGS [Tathagatagarbha Sutra] … the Mahaparinirvanasutra and the Lankavatarasutra characterize the tathagatagarbha explicitly as atman [Self].’
While in early Buddhist thought nirvana is characterized by permanence, bliss, and purity, it is viewed as being the stopping of the breeding-ground for the "I am" attitude, and is beyond all possibility of the Self delusion.