There are so many facets of Buddhism -one compliments the others-, the true embodiment of emptiness at the very heart of Buddhist teachings that nothing has an inherent existence of its own. No one does a better job than Robert Thurman, one of the most prominent Buddhist scholars representing the Mahayana school of thoughts, in giving a cerebral erudition of the meanings and interpretations of old manuscripts and their relevance to our contemporary life. That is represented, again, in his latest craft. The Mahayana tradition puts a huge emphasis on infinite and universal compassion for all sentient beings, it is the basis of every effort toward self-transformation, that ultimately entails self-transcendence in the selfless spirit of the altruistic mind seeking for enlightenment for the benefits of all. His book works on that basis in a very forceful, dense, idealistic fashion but accessible at the same time.
This Bodhisatva ideal is so infinitely lofty to the point that many people might find it impractical and unrealistic. However, as Thurman point-blankly elaborates throughout the book, that ideal isn't an empty dream of a romantic fool, but it's based on the infinite outlook of life with infinite room for personal growth; infinity that stretches to the "past" and "future" through infinite numbers of past and future lives, intimately intertwined and interrelated.
In this infinite universe, that is supported by science needless to say, there are infinite possibilities. That is one thing. The other is the proclamation that we are all Buddha now, we just need to be awakened to that fact. So if we are all enlightened beings with built-in infinite capacity for altruism and infinite deadlines to fulfill our Bodhisatva ideal, aiming high isn't that crazily unrealistic. If anything, it jumpstarts and single mindedly focus our commitment to practice to get closer to that ideal in our own pace and time.
This notion leads to a troubling theory (at least to some) of reincarnation that in Buddhism is more aptly coined as rebirth. How are the two different? And is there any scientific basis for either theory? Or is it a mere belief as theists believe in heaven or hell as the final destination after one's death?
Buddhism goes far deeper than a mere belief system which is an end to itself that gives you a not so comforting alternative of eternal damnation for stubbornly resisting to "see the truth." Buddhism is a sophisticated, surprisingly modern, consistent and scientific system of psychology. Thurman calls it "joyous science of the heart.
Some people who belongs to the hardcore materialist camp (usually atheists, scientists and thus, Nihilists) may just lump the Buddhist doctrine of rebirth as superstition and as unfounded as the belief in God, angels, heaven and hell of the theists. Their prejudice and dogmatism assumes that just as theistic belief in heaven is solely founded by the inherent fear of death, then so is the Buddhist doctrine of rebirth, unaware of the point blank assertion of the Buddha that birth, sickness, death are unavoidable facts of life and the failing world is a samsara (a cycle of birth and death) reeked in sufferings, the cure of which is Nirvana (liberation from the cycle which shouldn't be construed as extinction into nothingness, by the way). The Theravada tradition, which in a sense provides a basic interpretation of the Buddha's teachings, stops at that, while the Mahayanese, driven by infinite compassion for all beings, vows to delay the attainment of Nirvana until every single being is liberated.
So why rebirth? It boils down to the Buddhist tenet of selflessness. The self according to the Buddha is a relative and subjective reality that is not independent to myriad factors that create it in the first place. There is no enduring, unchanging part of it than in itself makes what we call "the self." The body and mind work together to become self, each of which is breakable into different elements that have also causes for their existence. To the Buddhists both matter and mind exist separately, yet interdependently. And Thurman points out something can't become nothing, it is scientifically unsustainable. The center of the contention between the Nihilists and the Buddhists is whether consciousness resides in the brain, whether the former is a mere side effect of physical activities of the neuron cells which will cease one the brain stops functioning and decays. The Nihilist materialists obviously believe so. The Buddhists don't, hence consciousness (or mind) is a something, a form or energy, and the law of physics dictates that energy can't be created nor destroyed.
In that sense both camps part ways in the move that seemingly lumps the Buddhists in the same league with the monotheist eternalists. However, the Buddhists warn us that even though there is a continuation of the mind, this mind is much less personal than the fixed soul that the eternalists hold onto so tightly. The mind (or the Buddhist relative soul) is fluid and so much less identifiable -hence selflessness- and is a fluctuative process driven by karma (in this case can be translated into obsessions and fixations).
Hence, Buddhism is literally sandwiched between two extremes of the atheist Nihilists and theist Eternalists, giving a candid point in case that the Buddha didn't call his Dharma "the Middle Path" for no reason.
On that basis then the rest of the book goes on with Seven Virtues of wisdom, generosity, justice, patience, creativity, contemplation and the art of infinite living to live a happy bountiful life, a life with minimum ego frictions and aggravations. In the nutshell, we can only be happy if we loosen up our ego boundaries, if we focus less in our self-preoccupations, realize the relativity of our "self" and start to care more about others since self and others are interchangeable. It is mighty difficult, needless to say, but we can gradually get there through practices outlined in this book. This is a message of hope, let's embrace it.