I do not have a strong theoretical grasp of the concept of rebirth, so I am wondering:
Is each Buddha that has existed/will exist the same being, reincarnated? Or is each Buddha a totally unrelated person from the previous Buddhas and Buddhas to come, who just happens to realize all of the same truths that the previous Buddha realized?
Thank you
Yes, they are totally different beings.
But Buddhism is saying that the very nature of your question is incorrect... that there is no self nor no-self. That these individuation of consciousness into selves is by itself incorrect for myriad reasons, one of them being that the 'new Buddha' could not exist without the 'old Buddha' ... and even the 'old Buddha' won't exist without the possibility of the 'new Buddha', someone to help This is especially because in order to become a Buddha, one's resolve for helping others (compassion paramita) must become completely pure, including taking the 1st Mahayana Vow to "not enter Nirvana until all beings are saved." We must look to the Mahayana to explain the concept of Buddahood because a Buddha is certainly different from an Arhat who would rather abide in emptiness (which is still helping beings) but that is another argument entirely..
Anyway, you won't understand till you are Enlightened yourself (not that I am) because the illusion of self-and-other is from whence your question comes in the first place.
Also, there is the perspective that bodhisattvas are nirmanakaya manifestations of the Buddha. So if you became Enlightened, it might be because you are a projection body of a Buddha (who has a spiritual parent as well)! Don't let this discourage you from practice though: this and the previous illusion mentioned are important at the Ultimate level of reality and in the relative senses of things, the answer reigns that yes, there is a relative person who mustered up the characteristics necessary to become a bodhisattva/Buddha and escaping forced rebirth and afflictions, consciously able to manifest myriad powers and help others according to causes and conditions.
Next Buddha is a totally unrelated separate person to previous Buddha. He will realize the same truth as previous Buddha when his(previous Buddha) teachings are no longer among us.
Once someone becomes Arahant, He will never be born again. The whole purpose of being Arahant is not to be born again.
How can previous Buddha can tell prophecy about next Buddha?
To be a Buddha, its saying we have to do lot of good Karma and endless sacrifices. Buddha can see someone's Karma and how these Karma going to effect them. Therefore, Buddha can see whose Karma is fulfilled to be next Buddha and when it happens.
As become a Buddha is so difficult, it's only for great persons who has endless courage and such a kind heart for all beings to preach them Dharma and make them aware of Samsara.
I think it's famously difficult to identity the Buddha; for example, in the Sariputta-Kotthita Sutta
Now, what more do you want, friend Kotthita? When a monk has been freed from the classification of craving, there exists no cycle for describing him.
Even so, Vaccha, any physical form by which one describing the Tathagata would describe him: That the Tathagata has abandoned, its root destroyed, made like a palmyra stump, deprived of the conditions of development, not destined for future arising. Freed from the classification of form, Vaccha, the Tathagata is deep, boundless, hard to fathom, like the sea. 'Reappears' doesn't apply. 'Does not reappear' doesn't apply. 'Both does & does not reappear' doesn't apply. 'Neither reappears nor does not reappear' doesn't apply.
"Any feeling... Any perception... Any fabrication...
"Any consciousness by which one describing the Tathagata would describe him: That the Tathagata has abandoned, its root destroyed, made like a palmyra stump, deprived of the conditions of development, not destined for future arising. Freed from the classification of consciousness, Vaccha, the Tathagata is deep, boundless, hard to fathom, like the sea. 'Reappears' doesn't apply. 'Does not reappear' doesn't apply. 'Both does & does not reappear' doesn't apply. 'Neither reappears nor does not reappear' doesn't apply.
That being so I don't see how it's possible to compare two Buddhas, to ask whether they're the same or different.
Asking the question might presume some Identity view (sakkāya-diṭṭhi), which the Buddha denied.
Apparently there's a Trikaya and Dharmakāya doctrine. I don't know, maybe you might want to say that all Buddhas are of the same Dharmakāya -- perhaps analagous to saying that there's no such thing as two different nirvanas. But Dhammakaya is not especially a Theravāda doctrine (except see also the 'Dhammakaya Movement of Thailand').
Which you believe will depend on tradition since it is impossible to determine without insight. Some believe he is a different being, others that he is a manifestation of the same entity. It does not really matter does it?
The lotus sutra may ease your curiosity, however there were many arrogant disciples who were frightened and could not bear to hear it. If you have a teacher you may want to ask them whether you should read it.
