(It is) suggested that she was in origin the numen of the storehouse who married Amaushumgalanna of the date harvest at the time the harvest was stored; also that her range was early extended to that of the storehouse generally, including wool, meat and grain.
In part, this may reflect a process of gradual unification of the fertility cults of the dual economies of Uruk, date-growing and husbandry, blending a date-god and a storehouse goddess (Amaushumgalanna and Inanna) with a different shepherd's god and goddess (Dumuzi and Inanna -the later conceivably a rain goddess.)
The Power in Rains
Still quite clear in the materials, is the aspect of Inanna as goddess of thunderstorms and rain, very close in character to her brother, Ishkur, and to Ninurta. As does Ninurta, she controls the lion-headed thunderbird, Imdugud. We hear of her letting it fly out of the house, and in the story "Enmerkar and the Lord of Aratta" it is called "the curb of Inanna put as bar in the mouth of all the world." in that story her method of forcing Aratta to submit to Uruk is to withhold rain and expose it to drought. The lion, typically an image or emblem of thunder gods such as Ishkur and Ninurta, occurs also with her. Her chariot is drawn by seven lions, she rides a lion, or she is herself a lion. The other thunder animal, the bull, is lent to her, albeit reluctantly by An when she wants the "Bull of Heaven" to kill Gilgamesh. Her character as the power in the thunderstorm is stated directly in the opening lions of a major hymn to her in which she is called "Inanna, the great dread storm of heaven."
Inanna describes herself as rain goddess more gently in a hymn where she says:
I step onto the heavens, and the rain
I step onto the earth, and the grass and herbs
But when she gets angry her outbursts are not merely tempestuous, they are truly the tempest itself, with its thunder shaking heaven and earth and its lightning burning and destroying.
This aspect of Inanna as a goddess of rain makes it more understandable that a persistent tradition linked her with the god of heaven, An, as his spouse, even to the point of identifying her with Antum; An was the sky seen as female and referred to the overcast sky, the clouds of which were "breasts of the sky" from which flowed the rain. Antum and Inanna represent the same phenomenon of nature, the power in the rain clouds. To the tradition of Inanna as a rain goddess, belongs also the Eclipse myth. There Inanna joins Ishkur and the storms in their attack on their father, the moon god, because she aspires to marry An and become queen of heaven, (which is one interpretation of her name). In the myth called the "Elevation of Inanna", the gods propose to An that he marry Inanna "with whom you have fallen in love," and this he readily does. He also confers on her his name and all his powers, then Enlil gives her his powers, and lastly Enki gives his to her. As queen of the universe she thus comes to unite in her person all its highest powers.
Goddess of War
In the process of humanization, gods of rain and thunderstorms tended to be envisaged as warriors riding their chariots into battle. Correspondingly we find that Inanna’s warlike character and skill with weapons is celebrated from early myths. In fact, battle was to the Sumerians "the dance of Inanna".
Morning and Evening Stars
Besides being a rain goddess and goddess of war, Inanna is also the goddess of the morning and evening star. A remarkable hymn from the time of Iddin-Dagan of Isin hails her as she rises in the sky in the evening. It tells how every month at the new moon she holds court for the gods to hear their petitions, how music is played for her and war games staged by her guardsmen attendants, ending in a mock parade of prisoners and perhaps not so mock shedding of blood. The hymn then returns to her in her character as the evening star, which marks the end of the day’s work for men and animals. All may go to rest while she, shining in the sky, judges the cases of just and unjust.
In the morning (as the morning star) she signals the awakening of man and beast. Copious offerings are brought to her and the personal gods of mankind approach her with their gifts of food and drink.
A further typical feature of the evening was the harlot setting out to pick up customers among the people returning from work in the fields; and perhaps because it was a common sight to see the harlot appear with the evening star there was a bond between them. Inanna is the protectress of the harlot as well as of the alehouse out of which she works. Moreover, the evening star is itself a harlot soliciting in the skies, and its power informs Inanna’s sisters below, making them incarnations of the goddess, their pickups, her bridegroom Dumuzi.
We see her as a charming, slightly difficult younger sister, as a grown daughter, and a worry to her elders because of her proclivity to act on her own impulses when they could have told her it would end in disaster. We see her as sweetheart, as a happy bride, and as a sorrowing young widow. We see her, in fact, in all the roles a woman may fulfill except the two which call for maturity and a sense of responsibility. She is never depicted as a wife and helpmate or as a mother.
In Inanna, then, an unusually interesting and complex character has come into being -so vividly that the natural background is gradually less felt. The numen of the storehouse, inevitably losing its young husband, the stores, is less and less sensed in Inanna’s loss of husbands or lovers. The power of a real thunderstorm is less and less felt behind Inanna’s tempestuous temper. The evening star rising when the harlots appear as if it were one of them, the ruttish powers of fecundation of the herds cease to explain Inanna’s wantonness and freedom with her favors. And her quick bolting with the "offices" from Eridu seems so characteristic that one inquires no further into the whys and wherefores of Inanna’s being the power in and behind the motley collection of a hundred or so activities which the myth so laboriously specifies. She is become truly all woman and of infinite variety.
(taken from "The Treasures of Darkness" by Thorkild Jacobsen, Yale University Press, 1976)