The devas and asuras fought bitterly and the devas emerged victorious. With victory came arrogance. In order to curtail the pride of the devas, the Supreme One appeared as Yaksa, said M.K. Srinivasan, in a discourse.
Indra sent Agni to find out who it was. Agni introduced himself to Yaksa, who asked Agni what his power consisted of. “I can burn up everything in the earth,” Agni replied. Yaksa placed a straw before Agni and asked him to burn it. But Agni could not. Vayu then approached Yaksa and said he could blow away everything on the earth. But when Yaksa placed a straw before him, Vayu found that he was powerless to blow even that away.
Indra then decided that he would himself find out who Yaksa was. But Yaksa disappeared. In the place of Yaksa there stood Uma Devi, the daughter of Himavan. Indra put his question to her: “Who was that Being?” And she said,” That was Brahman. The victory that you celebrate as yours was actually the victory of Brahman. He wanted you to shed your pride.” This story is narrated in the Kenopanishad. The Upanishad says that Brahman disappeared like a flash of lightning and in the wink of an eye. This is to show that even if we meditate upon Brahman, we are not capable of remembering Brahman for a long time. Brahman is also known as Vanam, indicating that He should be worshipped by all. How can knowledge of Brahman be attained? The Upanishad gives the answer. Knowledge about Brahman can be had through conquest of the senses and performance of Vedic sacrifices. Brahman resides in the Vedas and its six accessories — siksha (phonetics), vyakarana (grammar), chandas (prosody), niruktam (lexicography), jyotisham (astrology) and kalpa (knowledge of performance of rituals).