Hinduism

Reincarnation is the belief that an individual soul, or jiva, comes into the world and makes its way from a lowly condition to the very highest, that of liberation (moksha). In the Indian view, the soul is no more dependent on its body than the body is on the clothes it wears or the house it lives in. The growth of the soul up to the human stage is automatic, but with entry into a human body it attains self-consciousness and its growth takes a different form, involving free will, responsibility, and effort. When the jiva first enters a human body, it wants only the sensual pleasures of its new circumstances, and if these lead to savagery or cruelty, the soul may return to the body of an animal in its next life.

However, constant repetition of these pleasures becomes monotonous, and the jiva turns to social conquest, wealth, power, and fame to find satisfaction. When this second stage comes to appear trivial, the jiva turns towards the deeper satisfaction of responsibility in the community and commitment to the welfare of fellow humans. This third stage too must give way to the fourth and final state, which is release from reincarnation. The jiva is reborn according to its karma.

Buddhism

Buddhists, who also accept karma, do not view rebirth as a transmigration (for in Buddhism there is no distinct and separate soul that could pass from life to life), but each succeeding life must be considered the karmic effect of the previous life and the cause of the following one. What is reborn is a set of ‘tendencies’ that are caused by desire for human life and result in a cycle of rebirths. When a Buddhist ceases to desire life or to shun death (terms that cover all positive and negative thoughts and deeds), the ‘tendencies’ fall away and are not reborn. This, in personal terms, is liberation, or nirvana.

Western thought

In the West, although the belief was widespread up to the 4th century AD, reincarnation appears to have had no doctrinal origin, being rather a tenet of philosophical or mystical schools. Reincarnation is irreconcilable with the main body of Christian theology.