The Hinayanists looked upon Nirvana as an escape from the pains of life and death, a conception which to the Mahayanists with their Brahmanic background appeared as the old error of dualism. Thus the ideal man of the Hinayana was the arhat, one who simply attained Nirvana and ceased from rebirth, entering into the formless rest, bliss, and impersonality of the eternal. But the Mahayanists gave their philosophy of non-duality practical expression in the ideal of the bodhisattva, who attains liberation but remains in the world of birth and death to assist all other beings to enlightenment. In other words, they refused to make any absolute distinction between Nirvana and Samsara; the two states are the same, seen, as it were, from different points of view. Therefore the Lankavatara Sutra (as translated by D.T. Suzuki) says: "False imagination teaches that such things as light and shade, long and short, black and white are different and are to be discriminated; but they are not independent of each other; they are only different aspects of the same thing, they are terms of relation, not of reality. Conditions of existence are not of a mutually exclusive character; in essence things are not two but one. Even Nirvana and Samsara's world of life and death are aspects of the same thing, for there is no Nirvana except where is Samsara, and no Samsara except where is Nirvana. All duality is falsely imagined."
In terms of practical psychology this means that there is no actual distinction between our ordinary, everyday experience and the experience of Nirvana or spiritual freedom. But for some people this experience is binding and for others liberating, and the problem is to achieve what the Lankavatara calls that "turning about in the deepest seat of consciousness" which effects the transformation.
Now the Mahayana was more thoroughgoing in its statement of this problem than even Vedanta. For what is our ordinary, everyday experience? It is not just our awareness of external circumstances or even such ordinary activities as walking, eating, sleeping, breathing, and speaking; it includes also our thinking and feeling: our ideas, moods, desires, passions, and fears. In its most concrete form ordinary, everyday experience is just how you feel at this moment. In a certain sense Buddhism is very much a philosophy and a psychology of the moment, for if we are asked what life is, and if our answer is to be a practical demonstration and not a theory, we can do no better than point to the moment Now! It is in the moment that we find reality and freedom, for acceptance of life is acceptance of the present moment now and at all times.
Acceptance of the moment is allowing the moment to live, which, indeed, is another way of saying that it is to allow life to live, to be what it is now (yathabhutam). Thus to allow this moment of experience and all that it contains freedom to be as it is, to come in its own time and to go in its own time, this is to allow the moment, which is what we are now, to set us free; it is to realize that life, as expressed in the moment, has always been setting us free from the very beginning, whereas we have chosen to ignore it and tried to achieve that freedom by ourselves.
For this reason Mahayana Buddhism teaches that Nirvana or enlightenment cannot really be attained, because the moment we try to attain it by our own power we are using it as an escape from what is now, and we are also forgetting that Nirvana is unattainable in the sense that it already is.