Reincarnation is complicated.
Theosophists say reincarnation is necessary because it allows souls to bring knowledge from the “lower worlds” up to the “higher worlds”. What they call the monad, the divine spark or soul you get in your body, really belongs to three higher worlds – one spiritual, one intuitional and one higher mental. However, in order to get to these worlds, the monad needs to spend some time learning and growing in the lower mental, astral and physical worlds.
According to Hindus, the atman (soul) is immortal, but the body can and does die. It enters new bodies again and again through the cycle of samsara. Your karma is what influences what you’ll become when you reincarnate. For example, let’s say you are a bunny. Maybe you’re a good bunny, and you come back as a wolf, a bit higher up on the food chain. Or maybe you’ve been a bad bunny and you come back as some delicious plant.
In physics we learn that no energy is ever lost; only that it changes form. This is the common law of conservation of energy. Similarly, spiritual and mental action is never lost. It is transformed. Thus Karma is the law of the conservation of moral energy.
Eventually, though, you’ll stop reincarnating all together. At this point, known as moksha, (nirvana) your soul can be at peace – whatever that means.
Buddhists don’t really believe in any self that lives on when the body dies. With the body goes the person and the personality.
Instead, they believe that energy is transferred from body to body. An example would be the Daila Lama.
The Dalai Lama is considered not so much a reincarnation of one person, but a continuous incarnation of a particular bodhisattva (a figure who has reached enlightenment, but stays behind to help others do the same).
Apparently, Buddhists can find the up and coming Dalai Lama as a child, if they look for certain signs. Example: the current (14th) Dalai Lama remembers wanting to go to Lhasa (home of the Dalai Lama). Plus, his mother remembers him saying his teeth were in a certain box in a certain house, where they found a set of dentures belonging to the 13th Dalai Lama.
Also, the Dalai Lama remembers that when he was little, crows hung around his house for way longer than crows usually hang out. And this also happened to two previous Dalai Lamas.
Anyway, you would think that death wouldn’t be as complicated as life is but no no, we can never catch a break can we.
Personally, I’d like to merge the Buddhist and the Hindu versions of reincarnation and that would be:
You die. Your energy is conserved and transferred into a new body. That new body is not influenced by the things you did in your past life. It’s a fresh body where you can start off on a clean slate irrespective of whether you were good or bad in the past.
Now that I like.