Indra's weapons are the thunderbolt and lightning and he is the harbinger of the rains, which renders the earth fruitful.
To the Vedic people, the clouds that the winds brought from the ocean were enemies who held the treasures steadfast to themselves, until they were conquered by Indra and forced to pour them upon the parched soil.One of the greatest deeds performed by Indra is to release the waters held captive by the demons. There are a few legends connected with this theme. At times, the clouds are imagined as cows, which have been trapped in a cave by the demons. Indra rescues the cows after waging a war against the demons, signified by the thunder and lightning. The cows show their gratitude in loud bellowing cries, which mark the beginning of the rains.
According to the myth, the earth is scorched and dry because the rain clouds have been imprisoned by the demon of drought known as Vritra or Sushna. On hearing the pleas of the people Indra descends from his abode in the sky and is offered Soma, an intoxicating drink which is a favourite of Indra. Pleased with his reception, Indra asks the people how he can be of help. Hearing of their plight, he decides to fight the demons and rescue the rains. A graphic description of the battle details the commencement of the rainy season. At last the conflict is over, the rains descend and the earth is made fruitful.Vritra is described as
From earth withhold the genial showers;
Of mortal men the foe malign,
And rival of the race divine;
Whose demon hosts from age to age
With Indra war unceasing wage;
Who, time unnumbered crushed and slain,
Is ever newly born again,
And evermore renews the strife
In which again he forfeits life.
And soon the knell of Vritra's doom
Was sounded by the clang and boom
Of Indra's iron shower.
Pierced, cloven, crushed with horrid yell,
The dying demon headlong fell
Down from his cloud-built tower.
Now bound by Sushna's spell no more
The clouds discharge their liquid store;
And long by torrid sunbeams baked
The plains by their copious showers are slaked
The rivers swell, and seaward sweep
Their turbid torrents broad and deep
The peasant views with deep delight,
And thankful heart the auspicious sight.
His leafless fields so sere and sad,
Will soon with waving crops be glad;
And mother Earth, now brown and bare,
A robe of brilliant green will wear.