A post-Vedic version of the encounter between Indra and the demon Vritra is given in the “Vana Parva” section of _Mahābhārata_. Although it is coloured by the change which, in the process of time, passed over the religious beliefs of the Aryans, it retains some features of the original myth which are absent in the Vedic hymns. It should be understood that, at the period referred to, the belief obtained that the gods derived their powers from the saintly Rishis,[44] who fed them with sacrifices and underwent terrible penances, which enabled them to support or destroy the Universe at will. [44] The deified poets and sages. See Chapter VIII. It is related that in the Krita Age (the first Age of the Universe) a host of Dānāvas (giants and demons) were so strongly armed that they were invincible in battle. They selected the dragon Vritra as their leader, and waged war against the gods, whom they scattered in all directions. Realizing that they could not regain their power until they accomplished the death of Vritra, the Celestials appeared before their Grandsire, the Supreme Being, Brahma, the incarnation of the Soul of the Universe. Brahma instructed them to obtain the bones of a Rishi named Dadhicha, from which to construct a demon-slaying weapon. So the gods visited the Rishi and bowed down before him, and begged the boon according to Brahma's advice. Said Dadhicha: “O ye gods, I will renounce my body for your benefit.” Then the Rishi gave up his life, and from his bones the artisan god, Twashtri, shaped Indra's great weapon, which is called Vajra.[45] [45] Adolf Kaegi says: “Also Vadha or Vadhar”, which he compares with German, _Wetter_; O.H. German, _Wetar_: Anglo-Saxon, _Weder_; English, _Weather_. The original word signifying the sudden change in atmospheric conditions caused by the thunderstorm was ultimately applied to all states of the air. Twashtri spake to Indra and said: “With this, the best of weapons, O exalted one, reduce that fierce foe of the gods to ashes! And, having slain the foe, rule thou happily the entire domain of heaven, O chief of the celestials, with those that follow thee.”[46] [46] Roy's translation of _Mahabharata_.