Muni's PlayKena Upanishad: Part Third
The Third Part uses a parable to illustrate the supremacy of Brahman over all cosmic forces (Devas). After a victory, the Devas Agni (Fire), Vayu (Air), and Indra (King of Devas) became arrogant, believing the glory was theirs. Brahman appeared as a mysterious spirit (Yaksha) to humble them.
In the presence of this mysterious spirit, the Yaksha asks both Agni and Vayu the same two questions:
The Yaksha's Inquiry
Sanskrit: कः असि? तस्मिन् त्वयि किं वीर्यम्?
Transliteration: ko’sī? tasmim̐stvayi kiṃ vīryam?
Translation: Who art thou? What power resides in thee?
Neither Agni could burn nor Vayu blow away even a single straw, as their power was revealed to be dependent on Brahman.