Imagine a planet coalescing from dust in space. That is like our body and mind coming into being. Imagine the planet breaking apart and dissolving. That is like when we die. Imagine it coalescing again and reforming. That is like when we are born in our next life. The new planet is completely different, but drawn together from the same basic stuff. So the essence of mind is the same, but it comes together in a new way. Our karmic seeds are stored in a particular mindstream, so it's not quite like we dissolve into the ground of existence, lose all personal identity, and then something else reforms. But, just as my self in the future of this life is different than my current self, so my future rebirths are different. But the fact that there is karma in common means that of all the individuals in the universe in all of the three times (past, present and future), the ones I can influence the most are the ones that are future manifestations of my mindstream. I was at a retreat this past weekend, where Lama Norlha Rinpoche advised us that when we call upon the Buddhas, we need not limit ourselves to those in the past and present. We can and should also call upon the Buddhas of the future. Now it occurs to me that the final destination of the mindstream which I am a part of is Buddha. Therefore that future Buddha at the end of this mindstream is someone to whom I can call for help. This brings new meaning for me to the idea that we all have Buddha nature. In any event, in the same way that we should take care of the planet for its future inhabitants, we should take care of our body for its future inhabitants (future instances of our mindstream), and this means physically, mentally and spiritually. By performing actions that get us closer to Buddhahood, we are being kind to our future selves as well as to the vast array of sentient beings who can rely on us when we have achieved perfect enlightenment.
I think the analogy of the planet being destroyed and reformed is useful because it really shows that reincarnation is subtle. If the personality, the mental apparatus of conceptualization gets destroyed in between lives, then in what way can we say the new individual is the "same" as the old one. There are certain tendencies that are carried over, habitual patterns of fixation, attachment and aversion. Conversely patterns of concentration and mental stability arising from meditation can carry over as well. But is it the same person? Again, I am not the same person as I was a second ago, so I am certainly a dramatically different person than the next incarnation of this mindstream.
I know one reader of this blog believes in reincarnation but certainly thinks I've gotten it wrong, whereas another reader (you people know who you are!) does not believe in reincarnation. Why do I believe that things work roughly the way I've outlined? My first thought when I was wrestling with this earlier is that it's very unlikely I could prove that reincarnation happens. But then by the same token, it seems unlikely that it could ever be disproven, especially given our current paltry knowledge of what consciousness is. So then I decided to search for an argument that would increase my confidence in reincarnation and this was what I came up with. It is quite reasonable to me because a fundamental teaching of Buddhism is that the essence of mind is clear, lucid and unaffected by particular thoughts or conditions. When one meditates and has certain experiences with the Lama, one begins to perceive this directly. Thus through direct observation one glimpses the essence of mind, like the ocean with thoughts appearing as waves. This sort of analogy gets at it a little bit, but to really understand what I mean, you need to have a comparable meditative experience. And once one accepts this underlying substrate of the mind, it becomes reasonable to imagine that it would continue after the body dies. It's like the planet that is made out of dust, our mind is "made" of this substrate.
