Shakyamuni Buddha, when he died, entered paranirvana, never to reincarnate again.
It's not really true though that when you reach nirvana, you can no longer reincarnate, because Buddha reached nirvana already, while alive, under the Bodhi tree.
Many people seem to confuse nirvana with paranirvana as if they were the same thing.
Whatever it was that he realized, it is something you can realize while still alive. In some of the schools of Buddhism they say it is something you can see in any moment. That the reason we miss seeing this truth, finding our way to this realization, is not because it is hard to see, but because it is something we can see all the time, and is so obvious that we miss it.
So, as it is taught anyway, he was already free from the cycle of Samsara when he became enlightened. And he could continue to teach others after that - you don't kind of disappear in a puff of smoke when you become enlightened, and you don't have to die to be enlightened :).
Others could meet him and be taught by him due to their past connections and interactions, leading us to share the same world.
And according to the traditions, some Buddhas do reincarnate, and take on many physical forms to help others.
As to why it is that Shakyamuni Buddha entered paranirvana, while other Buddhas reincarnate, someone else needs to answer that, I don't know :).
I know that one story says that soon before he died, Shakyamuni Buddha hinted to his disciple Ananda that, if asked, he could stay in Samsara to help others, hinted three times, but Ananda didn't get the message and didn't ask him to stay, until it was too late.
It's not really true though that when you reach nirvana, you can no longer reincarnate, because Buddha reached nirvana already, while alive, under the Bodhi tree.
Many people seem to confuse nirvana with paranirvana as if they were the same thing.
Whatever it was that he realized, it is something you can realize while still alive. In some of the schools of Buddhism they say it is something you can see in any moment. That the reason we miss seeing this truth, finding our way to this realization, is not because it is hard to see, but because it is something we can see all the time, and is so obvious that we miss it.
So, as it is taught anyway, he was already free from the cycle of Samsara when he became enlightened. And he could continue to teach others after that - you don't kind of disappear in a puff of smoke when you become enlightened, and you don't have to die to be enlightened :).
Others could meet him and be taught by him due to their past connections and interactions, leading us to share the same world.
And according to the traditions, some Buddhas do reincarnate, and take on many physical forms to help others.
As to why it is that Shakyamuni Buddha entered paranirvana, while other Buddhas reincarnate, someone else needs to answer that, I don't know :).
I know that one story says that soon before he died, Shakyamuni Buddha hinted to his disciple Ananda that, if asked, he could stay in Samsara to help others, hinted three times, but Ananda didn't get the message and didn't ask him to stay, until it was too late.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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