they have not reached the truth that there is not self-substance in anything, nor have they attained the inconceivable transformation-death (acinty-parinama-cyuti). — Lankavatara Sutra
Death is the separation of the animative power of mind from the corporeal body (passive mind). Ordinary people have no knowledge of this inconceivable distinction. Their unbroken attachment to the corporeal body is all they have ever realized. Then to die, letting go of everything previously linked with the body, including the body, is truly perplexing.
But the mind that once animated the body continues. Its drive, prompted by habit-energy (vasana), is towards a resumption of the previous life, that is, towards a resumption of embodiment. To boot, nothing by way of the antecedent conditions necessary for rebirth has been sufficiently altered or superseded. And this is what Buddhism attempts to do: alter or supersede the necessary antecedents for rebirth.
But human consciousness is unwilling to take the first baby steps in this process. Human recorded history is not a history of getting off the wheel of samsara. Instead, it is a history of desire’s unremitting struggle to attain, within the context of human embodiment, its various goals all of which miss the transcendent. Thusly, it is an all-too-human struggle to borrow from Nietzsche.
Owning to its desire, the animative spirit of humankind is forever nailed to the tissue of biological being; that peering through its senses receives an extremely limited image of spirit’s work and its true nature (tathata). But what we perceive through our senses is only the filtrate of what true reality is not. And this includes the specter of death that hides the undying: the undying being nirvana as the supreme security from bondage to the wheel of samsara.
By comparison, the Bodhisattva (one who has had bodhicittotpada) who is aware of Mind’s true nature is also aware of the transformation or change of death (parinamacyuti) in which there is an inconceivable or unthinkable change of death into the undying (spirit as reflection into itself instead of reflection into other).
For the Bodhisattva, spirit, which previously attached to the false security of the flesh, has found itself so that it knows it need not depend on the temporal body anymore. In other words, spirit has become independent. Yet strangely, spirit has always been independent from its various creations. But never knowing itself, what could it do but believe that its creations were itself in which case it became bonded to them. As a result, it needlessly suffered countless rebirths into its phenomena.
If we see the undying within our being which is like a light that enlivens our body but is not subject to its death, we have significantly altered the antecedents of rebirth. By even accepting this, uncritically, we can rest assured that our next rebirth will be higher. On the other hand, to scout even the possibility of transcendence, believing that after death there is no more, we open the gates to endless suffering.