I consider the human being to be a matter of pure energy and like every other type of energy it cannot be destroyed except, perhaps, in a nuclear blast. When a body dies the energy doesn't dissipate but spreads into every other organic life and into the soil. One becomes all and nothing at the same time. At the end, your energy will accumulate into one being which will then result in a spawning of a new you. But this process is long and bothersome.