Perhaps the idea which has had the widest and most penetrating influence on Indian thought is that conception of the Universe which is known as Samsara, the world of change and transmigration.  The idea of rebirth and the wandering of souls from one body to another exists in a fragmentary form among savage tribes in many countries, but in India it makes its appearance as a product of ripening metaphysics rather than as a survival.  It plays no part in the Vedic hymns:  it first acquires importance in the older Upanishads but more as a mystery to be communicated to the elect than as a popular belief and to some extent as the special doctrine of the military class rather than of the Brahmans.  At the time of the Buddha, however, it had passed beyond this stage and was as integral a part of popular theology as is the immortality of the soul in Europe.

Such expressions as the transmigration of souls or metempsychosis imperfectly represent Indian ideas.  They are incorrect as descriptions of Buddhist dogmas, which start by denying the existence of a soul, and they are not entirely suitable to those Vedantic schools which regard transmigration as part of the illusory phenomenal world.  The thought underlying the doctrine is rather that as a child grows into youth and age, so the soul passes from life to life in continuity if not in identity.  Whatever the origin of the idea may have been, its root in post-Vedic times is a sense of the transitoriness but continuity of everything.  Nothing is eternal or even permanent:  not even the gods, for they must die, not even death, for it must turn into new life.

This view of life is ingrained in Indian nature.  It is not merely a scientific or philosophical speculation, but it summarizes the outlook of ordinary humanity.  In Europe the average religious man thanks or at least remembers his Creator.  But in India the Creator has less place in popular thought.  There is a disinclination to make him responsible for the sufferings of the world, and speculation, though continually occupied with the origins of things, rarely adopts the idea familiar to Christians and Mohammedans alike, that something was produced out of nothing by the divine fiat.  Hindu cosmogonies are various and discordant in details, but usually start with the evolution or emanation of living beings from the Divinity and often a reproductive act forms part of the process, such as the hatching of an egg or the division of a Divinity into male and female halves.  In many accounts the Deity brings into being personages who continue the work of world-making and such entities as mind, time and desire are produced before the material world.  But everything in these creation stories is figurative.  The faithful are not perplexed by the discrepancies in the inspired narratives, and one can hardly imagine an Indian sect agitated by the question whether God made the world in six literal days.