Buddhism is no different then the theory of evolution.Nirvana is simply a stilling or stepping back from the outgoing waves of mind, vital and matter. It is not supramentalization that leads to perfection and physical immortality. An individual who attains to nirvana moves out of the centrifugal and cyclical rhythms of consciousness and energy and can if he quits his body by drawing out his psychic stay aloof from the frontal workings of nature. He can if he so wishes re-enter the whirlpool and reincarnate in any family of his choosing if he wishes to help others attain to the same state of liberation or if he wishes to further his own development of consciousness by rising beyond nirvana. So, there's no contradiction.
It has no beginning, it relies on already created matter and energy.
In this case, the true Buddhist view is that the impersonal stream of consciousness flows on impelled by ignorance and craving from life to life. Though the process is impersonal, the illusion of personality continues as it does in this life.
In terms of Absolute Truth, there is no "immortal soul" that manifests in a succession of bodies, but in terms of the relative truth by which we are normally guided, there is a "being" that is reborn. In order to gain Enlightenment, it is necessary to come to a realization of the situation as it is according to absolute truth; in order to face and begin to understand the problem of death we can, in the first instance, view it in terms of that "relative truth" which normally rules our lives and which has its validity in its own sphere. We need merely, for the present, to remind ourselves that this is but a "provisional" view of things. In this connection, too, we have to observe that we are dealing only with the question of death as it affects the ordinary person, not one who has attained Enlightenment.
In other words our lives live on after death in the body of other people.
Nirvana enlightenment is obtained through the consciousness of other people after death.
A never ending pattern of consciousness.
Complete Hindu bull-shit.