In the Veda it was Indra who had to contend against Vritra and Ahi, _i.e._ the serpents, and the black spirits, which desired to drink up the water of the sky and veil its light. In Iran, as we shall see, this office is transferred to other spirits, and also to Thraetaona. The Azhi dahaka of the Avesta is the Ahi of the Veda. Ahi and Azhi are the same word, with the same meaning; the addition _dahaka_ refers to the destructive power of this demon. Verethraghna, _i.e._ the slayer of Vritra, stands in the Avesta at the side of Thraetaona in his struggle with Azhi (p. 35), and the morning wind supports him just as in the Veda the winds assist Indra against Ahi and Vritra. Among the Indians, Traitana is a spirit of the air, who dwells in the remotest regions of the sky, who hews off the head of a giant from his shoulders, and in the Veda, Trita, the son of Aptya, drinks the draught of Soma, in order to win strength for the slaying of Vritra; he slays the snake with three heads and seven tails; with his iron club he splits the hollows in the rock in which the demons have hidden the cows of the heaven (the rain clouds).[71] In the Veda, Aptya is the father of Trita; in the Avesta, Athwya is the father of Thraetaona. Of Trita, whom it represents as sprung from Çama, the Avesta declares that he was the first physician; in the Veda we are told of Trita he knew how to heal sickness as the gods had taken his sickness from him; that he bestowed long life.[72] The two figures of Trita and Traitana gradually unite in the Veda; in the Avesta, Thrita and Thraetaona remain separate persons. The Kereçaçpa of the Avesta seems to correspond to the Kriçaçva of the Indians, whom we first find in the Epos, where he is celebrated as a warlike Rishi.[73]