Such in bare outline is the main story of the Ramayana. By the addition of the first and last books Valmiki's epic has in the following way been transformed into a poem meant to glorify the god Vishnu. Ravana, having obtained from Brahma the boon of being invulnerable to gods, demigods, and demons, abuses his immunity in so terrible a manner that the gods are reduced to despair. Bethinking themselves at last that Ravana had in his arrogance forgotten to ask that he should not be wounded by men, they implore Vishnu to allow himself to be born as a man for the destruction of the demon. Vishnu, consenting, is born as Rama, and accomplishes the task. At the end of the seventh book Brahma and the other gods come to Rama, pay homage to him, and proclaim that he is really Vishnu, "the glorious lord of the discus." The belief here expressed that Rama is an incarnation of Vishnu, the highest god, has secured to the hero of our epic the worship of the Hindus down to the present day. That belief, forming the fundamental doctrine of the religious system of Ramanuja in the twelfth and of Ramananda in the fourteenth century, has done much to counteract the spread of the degrading superstitions and impurities of Çivaism both in the South and in the North of India. The Ramayana contains several interesting episodes, though, of course, far fewer than the Mahabharata. One of them, a thoroughly Indian story, full of exaggerations and impossibilities, is the legend, told in Book I., of the descent of the Ganges. It relates how the sacred river was brought down from heaven to earth in order to purify the remains of the 60,000 sons of King Sagara, who were reduced to ashes by the sage Kapila when his devotions were disturbed by them. Another episode (i. 52-65) is that of Viçvamitra, a powerful king, who comes into conflict with the great sage Vasishtha by endeavouring to take away his miraculous cow by force. Viçvamitra then engages in mighty penances, in which he resists the seductions of beautiful nymphs, and which extend over thousands of years, till he finally attains Brahmanhood, and is reconciled with his rival, Vasishtha.