When one body dies, it is as if one piece of fuel were
burnt: the vital process passes on and recommences in another and so
long as there is desire of life, the provision of fuel fails not.
Buddhist doctors have busied themselves with the question whether two
successive lives are the same man or different men, and have illustrated
the relationship by various analogies of things which seem to be the
same and yet not the same, such as a child and an adult, milk and curds,
or fire which spreads from a lamp and burns down a village, but, like
the Brahmans, they do not discuss why the hypothesis of transmigration
is necessary. They had the same feeling for the continuity of nature,
and more than others they insisted on the principle that everything has
a cause. They held that the sexual act creates the conditions in which a
new life appears but is not an adequate cause for the new life itself.
And unless we accept a materialist explanation of human nature, this
argument is sound: unless we admit that mind is merely a function of
matter, the birth of a mind is not explicable as a mere process of cell
development: something pre-existent must act upon the cells.

Europeans in discussing such questions as the nature of the soul and
immortality are prone to concentrate their attention on death and
neglect the phenomena of birth, which surely are equally important. For
if a soul survives the death of this complex of cells which is called
the body, its origin and development must, according to all analogy, be
different from those of the perishable body. Orthodox theology deals
with the problem by saying that God creates a new soul every time a
child is born[35] but free discussion usually ignores it and taking an
adult as he is, asks what are the chances that any part of him survives
death. Yet the questions, what is destroyed at death and how and why,
are closely connected with the questions what comes into existence at
birth and how and why. This second series of questions is hard enough,
but it has this advantage over the first that whereas death abruptly
closes the road and we cannot follow the soul one inch on its journey
beyond, the portals of birth are a less absolute frontier. We know that
every child has passed through stages in which it could hardly be called
a child. The earliest phase consists of two cells, which unite and then
proceed to subdivide and grow. The mystery of the process by which they
assume a human form i