To the more advanced anthropomorphism of Indra's nature are due the occasional immoral traits which appear in his character. Thus he sometimes indulges in acts of capricious violence, such as the slaughter of his father or the destruction of the car of Dawn. He is especially addicted to soma, of which he is described as drinking enormous quantities to stimulate him in the performance of his warlike exploits. One entire hymn (x. 119) consists of a monologue in which Indra, inebriated with soma, boasts of his greatness and power. Though of little poetic merit, this piece has a special interest as being by far the earliest literary description of the mental effects, braggadocio in particular, produced by intoxication. In estimating the morality of Indra's excesses, it should not be forgotten that the exhilaration of soma partook of a religious character in the eyes of the Vedic poets. Indra's name is found in the Avesta as that of a demon. His distinctive Vedic epithet, Vritrahan, also occurs there in the form of verethraghna, as a designation of the god of victory. Hence there was probably in the Indo-Iranian period a god approaching to the Vedic form of the Vritra-slaying and victorious Indra. In comparing historically Varuna and Indra, whose importance was about equal in the earlier period of the Rigveda, it seems clear that Varuna was greater in the Indo-Iranian period, but became inferior to Indra in later Vedic times. Indra, on the other hand, became in the Brahmanas and Epics the chief of the Indian heaven, and even maintained this position under the Puranic triad, Brahma-Vishnu-Çiva, though of course subordinate to them. At least three of the lesser deities of the air are connected with lightning. One of these is the somewhat obscure god Trita, who is only mentioned in detached verses of the Rigveda. The name appears to designate the "third" (Greek, trito-s), as the lightning form of fire. His frequent epithet, Aptya, seems to mean the "watery." This god goes back to the Indo-Iranian period, as both his name and his epithet are found in the Avesta. But he was gradually ousted by Indra as being originally almost identical in character with the latter. Another deity of rare occurrence in the Rigveda, and also dating from the Indo-Iranian period, is Apam napat, the "Son of Waters." He is described as clothed in lightning and shining without fuel in the waters. There can, therefore, be little doubt that he represents fire as produced from the rain-clouds in the form of lightning. Matariçvan, seldom mentioned in the Rigveda, is a divine being described as having, like the Greek Prometheus, brought down the hidden fire from heaven to earth. He most probably represents the personification of a celestial form of Agni, god of fire, with whom he is in some passages actually identified. In the later Vedas, the Brahmanas, and the subsequent literature, the name has become simply a designation of wind.