Shakyamuni Buddha passed away at the age of 80 under twin sala trees near the town of Kushinagara. We are very familiar with this name of the town as we recite this name every time when setting out eating bowls, intoning "Buddha was born in Kapilavastu, enlightened in Magadha, taught in Varanasi, entered nirvana in Kushinagara..."
We sometimes call his death "the Buddha's Entering Nirvana," but, strictly speaking, the Buddha was a person who had already attained nirvana when enlightened under the bodhi tree and he always remained in that state. So it is problematic to use this term only for his death. Therefore later Buddhists assumed two types of nirvana;
nirvana-with-body and nirvana-without-body. If this idea is applied, we can say the Buddha was in the state of nirvana-with-body while he was alive and entered nirvana-without-body when he was dead.
But I think this is still problematic. In their doctrine of two types of nirvana, nirvana-with-body is imperfect compared to nirvana-without-body. They think as far as we have a body in this world, we can not attain a perfect nirvana because it is impossible to eradicate all delusions while having a body. It implies that we need to die to attain a perfect nirvana or we have to give up attaining nirvana in this world. Is this really the Buddha's message?
In Mahayana Buddhism there is a phrase, "Without eradicating delusion, we attain nirvana". Here nirvana is not an ideal world somewhere far away from us but a world of reality in which we are living here and now. Nehan-e is a good opportunity for us rethink about a very important concept in Buddhism, nirvana, being guided by "if you can understand that birth and death are Nirvana itself, there is not only no necessity to avoid them but also nothing to search for that is called Nirvana." These are Dōgen's words in Shoji (Birth-Death).
In the Soto Zen tradition, we perform a special ceremony, Nehan-e, to commemorate the Buddha's death and express our gratitude to him on February 15th. Nehan-e is one of the three most important commemoration days in the Soto Zen tradition. It is one of the three Buddha memorials (San Bukki): Nehan-e (Buddha's Nirvana assembly), Gotan-e (Buddha's birthday assembly) and Jodo-e (Buddha's attainment assembly).
For this ceremony, temples hang a big scroll depicting the Buddha entering nirvana. In the painting, the Buddha is lying on his right side in a grove of sala trees, his head toward the north and his face toward the west. He is surrounded by weeping gods, humans, and animals.
We, as Buddhists, should know what his last words were, his last message in this world. According to Mahaparinibbana Sutta, he said to the bhikkhus, "Behold now, bhikkhus, I exhort you: All compounded things are subject to vanish. Strive with earnestness!" This was the last word of the Buddha.
This sounds almost too ordinary to be the last words of a great person revered as a "World Teacher." But this should be deeply understood as the essence of his whole teaching.
The teaching of impermanence is telling us that anguish, worry, sadness, and suffering come from the delusion of taking the impermanent as the permanent. To clarify this, the Buddha further taught that the five aggregates (our body and mind) were not the permanent selves. Thinking of body and mind as a permanent self, we tightly cling to it. This is a core of all delusions.
The teaching of impermanence also encourages the Buddha's disciples to strive to practice diligently. If they are forgetful about the fact that they are impermanent and mortal, they might reserve today's practice for tomorrow and make light of the practice. There is no guarantee that we will be alive tomorrow. If we wish to accomplish the practice and attain nirvana, the ultimate peace in this lifetime, we should strive to practice with full earnestness.
This is what the Buddha meant by his last words. And he himself was a great living example who lived out a life of what he said in his last words. Why don't we follow him?
Finally I would like to introduce to you a verse titled "Buddha's Nirvana" composed by Zen master Daichi as an incense phrase for the celebration of Nehan-e;
Willow trees are dark and flowers are bright. It is February of spring.
In a grove of sala trees the Buddha manifested and moved toward nirvana.
Venerable Chunda tried to cover Buddha's corpse with white cloth but could not do it.
Buddha's radiant golden body was fully exposed.
This verse is saying that nirvana is eternal and permeates throughout the whole universe and can't be covered by the limited cloth of our conceptual grasping. It is fully exposed everywhere, as spring scenery of dark willows and bright flowers.
Buddha's entering nirvana is a skillful means to teach us about impermanence and he is actually dwelling in the whole world forever. That is why Nirvana Assembly Statement begins by intoning, "The pure body of the dharma realm fundamentally has no emerging or disappearing. The power of the vow of great compassion is manifest throughout the goings and comings..."