All Life Is Yoga: Death and Rebirth

"Even if Science – physical Science or occult Science – were to discover the necessary conditions or means for an indefinite survival of the body, still, if the body could not adapt itself so as to become a fit instrument of expression for the inner growth, the soul would find some way to abandon it and pass on to a new incarnation. The material or physical causes of death are not its sole or its true cause; its true inmost reason is the spiritual necessity for the evolution of a new being." – Sri Aurobindo