As the Kena Upanishad tells it
Kena Upanishad, parts 3 and 4 · 2 min read
The gods had won a great victory.
It was not really theirs. Brahman, the power that stands behind everything, had won it for them. But the gods did not see that. They looked at the field and felt very pleased with themselves.
"This victory is ours," they said. "This greatness is ours alone."
Brahman knew what they were thinking, and appeared before them.
The gods stared. Something was standing there that they had never seen before, and not one of them could say what it was.
"What is this spirit?" they whispered.
They turned to Agni, the fire. "Agni, you know everything that is born. Go and find out what this is."
"I will," said Agni, and he hurried towards it.
"Who are you?" the spirit asked him.
"I am Agni," he said. "I am Jatavedas, the knower of all that is born."
"And what power is in you?"
"I can burn everything there is on this earth," said Agni.
The spirit laid a single blade of dry grass on the ground in front of him.
"Burn this."
Agni went at it with all his strength. He blazed and roared. The blade of grass lay where it was, not even singed.
He went back to the gods. "I could not find out what that spirit is," he said.
Then they turned to Vayu, the wind. "Vayu, go and find out what this is."
"I will," said Vayu, and he rushed towards it.
"Who are you?" the spirit asked.
"I am Vayu. I am the one who moves through the sky."
"And what power is in you?"
"I can carry off everything there is on this earth," said Vayu.
The spirit set the blade of grass before him.
"Carry this off."
Vayu threw himself at it with all his speed. The blade of grass did not stir.
He went back to the gods. "I could not find out what that spirit is."
Then the gods turned to their king.
"Indra, generous one, you go."
"I will," said Indra, and he went towards it.
The spirit did not question him. It did not set him any test. As he came near, it simply vanished.
Indra stood alone in the empty place. He did not go back to the others, and he made no boast. He stayed where he was, and in that same spot a woman appeared before him, shining and beautifully adorned. She was Uma, the daughter of Himavat, the snow mountain.
Indra asked her. "Who was that spirit?"
"That was Brahman," said Uma. "It was Brahman's victory, and you have all been glorying in it as if it were your own."
Then Indra understood.
The Upanishad adds a short note. Agni, Vayu and Indra stand above the other gods because they came nearest to Brahman. And Indra stands above those two, because he was the first to know what it was.