As to the notion of Nirvana as held by disciples and masters who still cling to the notion of an ego-self, and who try to find it by going off by themselves into solitude: their notion of Nirvana is an eternity of bliss like the bliss of the Samádhis-for themselves. They recognize that the world is only a manifestation of mind and that all discriminations are of the mind, and so they forsake social relations and practice various spiritual disciplines and in solitude seek self-realization of Noble Wisdom by self-effort. They follow the stages to the sixth and attain the bliss of the Samádhis, but as they are still clinging to egoism they do not attain the "turning-about" at the deepest seat of consciousness and, therefore, they are not free from the thinking-mind and the accumulation of its habit-energy. Clinging to the bliss of the Samádhis, they pass to their Nirvana, but it is not the Nirvana of the Tathágatas. They are of those who have "entered the stream"; they must return to this world of life and death.
Then said Mahamati to the Blessed One: When the Bodhisattvas yield up their stock of merit for the emancipation of all beings, they become spiritually one with all animate life; they themselves may be purified, but in others there yet remain unexhausted evil and un-matured karma. Pray tell us, Blessed One, how the Bodhisattvas are given assurance of Nirvana? And what is the Nirvana of the Bodhisattvas?
The Blessed One replied: Mahamati, this assurance is not an assurance of numbers nor logic; it is not the mind that is to be assured but the heart. The Bodhisattva’s assurance comes with the unfolding insight that follows passion hindrances cleared away, knowledge hindrance purified, and ego-less-ness clearly perceived and patiently accepted. As the mortal-mind ceases to discriminate, there is no more thirst for life, no more sex-lust, no more thirst for learning, no more thirst for eternal life; with the disappearance of these fourfold thirsts, there is no more accumulation of habit-energy; with no more accumulation of habit-energy the defilements on the face of the Universal Mind clear away, and the Bodhisattva attains self-realization of Noble Wisdom that is the heart’s assurance of Nirvana.
There are Bodhisattvas here and in other Buddha-lands, who are sincerely devoted to the Bodhisattva’s mission and yet who cannot wholly forget the bliss of the Samádhis and the peace of Nirvana-for themselves. The teaching of Nirvana in which there is no substrate left behind, is revealed according to a hidden meaning for the sake of these disciples who still cling to thoughts of Nirvana for themselves, that they may be inspired to exert themselves in the Bodhisattva’s mission of emancipation for all beings. The Transformation-Buddhas teach a doctrine of Nirvana to meet conditions as they find them, and to give encouragement to the timid and selfish. In order to turn their thoughts away from themselves and to encourage them to a deeper compassion and more earnest zeal for others, they are given assurance as to the future by the sustaining power of the Buddhas of Transformation, but not by the Dharmata-Buddha.
The Dharma, which establishes the Truth of Noble Wisdom, belongs to the realm of the Dharmata-Buddha. To the Bodhisattvas to the seventh and eighth stages, Transcendental Intelligence is revealed by the Dharmata-Buddha and the Path is pointed out to them, which they are to follow. In the perfect self-realization of Noble Wisdom that fallows the inconceivable transformation death of the Bodhisattva’s individualized will-control, he no longer lives unto himself, but the life that he lives thereafter is the Tathágata’s universalized life as manifested in its transformations. In this perfect self-realization of Noble Wisdom the Bodhisattva realizes that for the Buddhas there is no Nirvana.
The death of a Buddha, the great Parinirvana, is neither destruction nor death, else would it be birth and continuation. If it were destruction, it would be an effect-producing deed, which is not. Neither is it a vanishing nor abandonment, neither is it attainment, nor is it of no attainment; neither is it of one significance nor of no significance, for there is no Nirvana for the Buddhas.
The Tathágata’s Nirvana is where it is recognized that there is nothing but what is seen of the mind itself; is where, recognizing the nature of the self-mind, one no longer cherishes the dualisms of discrimination; is where there is no more thirst nor grasping; is where there is no more attachment to external things. Nirvana is where the thinking-mind with all its discriminations, attachments, aversions and egoism is forever put away; is where logical measures, as they are seen to be inert, are no longer seized upon; is where even the notion of truth is treated with indifference because of its causing bewilderment; is where, getting rid of the four propositions, there is insight into the abode of Reality. Nirvana is where the twofold passions have subsided and the twofold hindrances are cleared away and the twofold ego-less-ness is patiently accepted; is where, by the attainment of the "turning-about" in the deepest seat of consciousness, self-realization of Noble Wisdom is fully entered into, that is the Nirvana of the Tathágatas.
Nirvana is where the Bodhisattva stages are passed one after another; is where the sustaining power of the Buddhas upholds the Bodhisattvas in the bliss of the Samádhis; is where compassion for others transcends all thoughts of self; is where the Tathágata stage is finally realized.
Nirvana is the realm of the Dharmata-Buddha; it is where the manifestation of Noble Wisdom that is Buddhahood expresses itself in Perfect Love for all; it is where the manifestation of Perfect Love that is Tathágata-hood expresses itself in Noble Wisdom for the enlightenment of all- -there, indeed, is Nirvana!
There are two classes of those who may not enter the Nirvana of the Tathágatas: there are those who have abandoned the Bodhisattva ideals, saying, they are not in conformity with the sutras, the codes of morality, nor with emancipation. Then there are the true Bodhisattvas who, on account of their original vows made for the sake of all beings, saying, "So long as they do not attain Nirvana, I will not attain it for myself," voluntarily keep themselves out of Nirvana. But no beings are left outside by the will of the Tathágatas; some day each and every one will be influenced by the wisdom and love of the Tathágatas of Transformation to lay up a stock of merit and ascend the stages. But, if they only realized it, they are already in the Tathágata’s Nirvana for, in Noble Wisdom, all things are in Nirvana from the beginning.
http://www.buddhistinformation.com/l...tara_sutra.htm