visvasyanu yuge yuge
hanyante yais trayi-dvisah
In each age, the infallible Lord appears in this world among the animals, human beings, sages and demigods. By His activities in these incarnations He protects the universe and kills the enemies of Vedic culture.
The protective activities of the Lord, indicated by the word raksa, constitute one of the ten fundamental topics of a Maha-purana, or a great Puranic literature.