The term avatâra is usually associated with divine incarnations, especially the ten incarnations of Vishnu. But there were lists with as many as twenty-six incarnations. The ten avatâras, dashâvatâra (dasha, “ten,” and avatâra, “incarnations”), were Matsya the fish, Kûrma the turtle, Varâha the boar, Narasimha the lion-man, Vâmana the brâhmacâri (second stage of life) dwarf, Paras´u-Râma (or Râma with the ax), Shrî Râma, Balabhadra-Râma, Krishna, and the future avatâra, Kalki.
The incarnation of Vishnu as Kalki is expected at the end of the Kali Yuga when this evil age ends in fire. One account stated that there are an innumerable number of the incarnations of Vishnu, both partial (amsâvatara) and full. In some lists the Buddha was considered an incarnation of Vishnu, taking upon himself the form of a false teacher in order to lead those who were evil away from the Vedas.
Traditionally, each avatâra appeared in order to perform a specific cosmic duty that was necessary to maintain or restore cosmic order. Having performed that task, the avatâra then disappeared, or merged back into Vishnu. The myths of each of the avatâras will be told under its own heading, but those of Râma and Krishna need further attention. These deities became so popular that they transcended their regional origins.
As early as medieval Hinduism, each began to be seen as a deity in his own right, and indeed as the supreme lord of the universe, not just an incarnation of Vishnu. This change also involved a reversal. Since either Râma or Krishna was the Supreme, then Vishnu, and all other gods for that matter, were but manifestations of Râma or Krishna. The myths about the Divine Mother, Devî (Durgâ), and S´iva also involved the notion of divine descents (avatâra).
But there were subtle differences in the philosophical and theological concepts of S´âktism (worship of the Divine Mother) and Shaivism (worship of S´iva). Both maintained philosophically that the Absolute did not come down into the limitations of time, space, and causality. The Absolute remained beyond these limitations, while only a manifestation, not technically an avatâra, appeared to reveal the truth or to correct what only God could. Krishna’s promise in the Bhagavad Gîtâ expressed the concept well:
In order to protect the good and punish the wicked,
In order to make a firm foundation for righteousness,
I come into being age after age.(Bhagavad Gîtâ 4.7–8)