The 'Hindu' Dharmic tradition tells us that we are spirit souls passing through material bodies eternally if we do not liberate ourselves from this life and death cycle. Moksha, this liberation process, allows us to live eternally in the spiritual world. It is, or should be, our goal to achieve immortality in this spiritual sense, to ascend past the eternal cycle of incarnation and living in eternal bliss at home in the heavens. Due to my imperfect knowledge on this subject, this article will be more of a brainstorm, rather than an exposition.
Reincarnation is one of the most misunderstood elements of 'Eastern traditions' such as Hinduism and Buddhism. Some believe that according to the laws of thermodynamics you are energy and on a macro-scale, nothing is removed or created from the universe; all energy is transformed from one thing into another. On the micro-scale on the other hand, we are reborn with every breath, no longer beholden to our past selves. Consciousness shouldn’t be any different to this paradigm. As we know that energy is recycled, we may also hypothesise that your DNA can also carry encoded information from the past material experiences in your bloodline.
I find it to be wonderful that reincarnation is becoming a mainstream topic of discussion among many age groups. Similarly, the question of the meaning of life is often pondered but this seems to be more quantity than quality of discussion. I believe there is some truth behind reincarnation, as our experience in the material world can't always accurately explain spiritual phenomenons. Repeatedly going through this world is just as strange as going through our days, months and years. Everything movies cyclically, everything ends and starts again.
Studying the lectures of spiritual teachers engaged in spiritual life tells us that everyone possesses a soul, and further, that in actuality we are spirit souls in material bodies. We pass through the eternal cycle of life and death gaining new bodies after each life, and it is my belief that our dreams can act as subconscious reflections into our past lives. Dreams have meanings, but deciphering the dreams can often reveal truths that are relevant to our present material life or past lives. Good dreams can mean a good life that was noble, and bad dreams denote a bad or corrupt previous life. In that same vein of thought, nightmares are likely the blood memories of traumatic events in our previous material lives. Dream dictionaries are handy for defining a dream but I find they aren’t extensive enough and often lack in certain areas regarding specific themes. If your current life is bad, you have negative karma to pay off, else you risk turning into a lower lifeform in your next life (transmogrification). As we are spiritual beings, it is quite likely that our spirits are continually affected by previous lives.
It is the key images that you retain in your head after a dream that is important to follow up with. If a dream is vivid enough that you remember seeing something, that could be your soul translating an event from a past life and telling that to your mind while you're asleep. I often hear people say they have dreams about things that don’t connect to their current life, but the dream is so vivid that it makes the dreamer think it really happened to them.
Bill Hicks once said that we are all one consciousness - the spirit souls that we are come from God - experiencing itself subjectively. I think there is some truth to this, but I am puzzled as to how everyone can have a soul if we are constantly increasing Earth's population but also engaging in Moksha. Where do these new spirit souls come from if souls are eternal and can't be created or destroyed? Perhaps some people are being born for the first time as material humans and as new souls, which may explain why some people have no instincts or blood memories and poor senses of self-preservation against predators of any kind? I would also like to know if we get the soul memories of our ancestors since we get their material DNA passed down to us, and if Déjà Vu is just the prediction of future events. Krishna (God) knows all that has happened, is happening and will happen, so it may be possible that because God knows us, he is instilling those visions in us for a reason.
"O Arjuna, as the Supreme Personality of Godhead, I know everything that has happened in the past, all that is happening in the present, and all things that are yet to come. I also know all living entities; but Me no one knows." - Bhagavad Gita 7.26
Buddhists believe in the 'I-POV', or that the experiencing subject suffers no discontinuities. That is, the transition to a new life with a new personality and a new set of memories doesn't disrupt consciousness, it seamlessly flows from one to the next. I believe that there is a disconnect of a handful of months until the spirit soul is successfully reawakened in a baby's body in utero. But since that consciousness, as they believe, is never disrupted, the idea of associating a particular life with a soul is generally rejected in Buddhism because the details of each life are merely additions to the conscious experience of that soul. Others believe we are the same being as the very first lifeform in an unbroken chain of reproduction.
Norse Pagans hold the view that "we are our ancestors, actualised. We are sentient and conscious (most of the time) manifestations of the world (the world tree Yggdrasil). We are not separate from nature and our souls are recurring images of past experiences. The Yggdrasil can be at the same time understood as nature, the universe or the world, as the nine worlds, the nine solar months of human pregnancy, and the tree of our ancestors, the embodiment of which we are leaves and fruits. It can be seen as 'Heimdallr', the whitest of Gods, the God ancestor of Europeans." They emphasise the point that you have the combined genetic material experiences of all your forefathers before you.
In a similar vein, others believe that when someone dies it's like pouring a glass of water into the ocean, and when a new life is born, a cup is filled from that source. All lives exist at once, and reincarnation is just a communication between the same spiritual lives across timelines beyond the conventional view of time. Our energy may even meet up with other energy of ours once we have died, which could explain child prodigies or stories of people knowing where their body was buried in a past life.
I believe the ideal life is one that is engaged in devotional practice towards God in whatever way is possible. Spirituality is an important institution to uphold in one's life, family household and school. For a greater scientific explanation of spiritual understanding, I think there should be a Brahmin-like caste that can experiment with hallucinative drugs to extend this understanding further, but at the same time, I think sticking to the regulative principles is the noblest way to live. Combine this with chanting the Hare Krishna Maha Mantra and you can cleanse your soul and your past lives' mistakes. Idealism is important in life to purify your soul for the next body you get. We must not get distracted by small things in our current life, or else our soul may gather more sins and take that negative karma into our next life to be purified. Live life nobly as if we will (and we will) have to go through that cycle again, for the sake of our next body and life.