Reincarnation is the most famous concept that people associate with Hinduism, Buddhism and Jainism. Let's see, from the perspective of historical materialism, how this concept was formed and what it means.
The Aryans' Vedas do not speak of reincarnation
If we look at the history of what is now India, we can see that conquerors came from the West and triumphed because of their military superiority. Those conquerors were “Aryans”, also called “Indo-Iranians.”
Indeed, we find similarities in the sacred texts of both the Aryans of Iran and of India, i.e. in the “avesta” and in the “ṛgveda”.
Those texts expressed the Aryans' vision of the world; in addition to the ṛgveda, we also find in India the Sama-Veda, the Yajur-Veda, and the Atharva-Veda. And thus, we cannot find the principle of reincarnation in the commonly named “Vedas”.
Why this? Because the aryans were patriarchal tribes, described in the ṛgveda as semi-nomadic pastoralists, who assembled in groups of warriors to launch raids under the supervision of a chief (a “raja” which gave the word “raj”, king, in India) and the “support” of priests (called “brahma”).
For this reason, the question of life after death was patriarchal. The dead fighter either went north, towards the Gods (devayaana), or he went south, towards the father (pitryaana).
The conquests, the raids, etc. fundamentally structured these tribes' vision of the world. They saw themselves as “chosen” by the Gods, and thus justified their military expeditions.
The Aryan's colonization and the Upanishads as birth of Brahmanism
When the Aryans settled in what is now North India and Pakistan, their vision of the world had to change, not only in a way that concerned them, but also in relation to the peoples that they had colonized.
In the process, the later vedas divided society into two: on one side the conquerors who became equal rulers as Brahmanas, Kshatriyas, Vaishyas (priests, warriors, landowners), and on the other side the Shudras, whose task was to serve the rulers.
Finally, this gave birth to the “Vedanta”, “the end of the Vedas”, called also “Upanishad”, which formulated the general conception of the caste system.
The concept was in fact a cross between the conception of the Aryans and the animist conception of the conquered peoples.
Animism attributes a spiritual essence to everything that lives: humans, animals, plants, considered as interrelated. It is certain that this animism was very developed, as the peoples conquered by the Aryans were the successors to the Indus Valley civilization, also called the Harappan Civilization.
We know very little about this very important historical civilization; more than a thousand towns and settlements have been found, such as the famous Mohenjo-daro, which dates from around 2500 BC, thus coinciding or being even before with the civilizations of Egypt, Mesopotamia and Crete.
The Aryans created a religion building on this animist principle of inter-related life, but combined it with the life-after-death of their own tradition. It became a system of reincarnation that justified the existence of the upper castes: to be reincarnated in theses castes depended on how much you respected religious values.
The subjected population had a “chance”, once reborn, to become part of the upper classes. In order to build a religion common to both the rulers and the ruled, the world was considered as not really valuable, the real goal being to “disappear from it”.
This was necessary to mask the class contradictions and to formulate religion not only in terms of classes, and the concept used was Yathaakarman, which means “from one stage to another”.
In one of the first Upanishads, the Chāndogya Upanishad, it is explained that the souls of the deaths move to the moon, come back after a while through rain, are hosted in the plants, are then eaten by the humans and the animals, and can then be found in semen.
In this Upanishad, we can read (5, 10, 7 and 8):
“Those whose conduct here on earth has been good will quickly attain good birth—birth as a brahmin, birth as a kshatriya, or birth as a vaisya. But those whose conduct here has been evil will quickly attain evil birth—birth as a dog, birth as a pig, or birth as a chandala.
8. "Those who neither practise meditation nor perform rituals follow neither of these ways. They become those insignificant creatures which are continually revolving and about which it may be said: ‘Live and die.’”
This is the classical construction of reincarnation in Brahmanism, based on the Vedism of the Aryan conqueror (the word aryan meaning “noble”), and mixed with the animism of the conquered and submitted peoples, as formulated around 600 BC.