BṚHADĀRAṆYAKA UPANISHAD · 1.2.1

नैवेह किं चनाग्र आसीत् ।
मृत्युनैवेदम् आवृतम् आसीद् अशनायया ।
अशनाया हि मृत्युः ।
तन् मनो ऽकुरुतात्मन्वी स्याम् इति ।
सो ऽर्चन्न् अचरत् ।
तस्यार्चत आपो ऽजायन्त ।
अर्चते वै मे कम् अभूद् इति ।
तद् एवार्क्यस्यार्कत्वम् ।
कं ह वा अस्मै भवति य एवम् एतद् अर्क्यस्यार्कत्वं वेद ॥

naiveha kiṃ canāgra āsīt ।
mṛtyunaivedam āvṛtam āsīd aśanāyayā ।
aśanāyā hi mṛtyuḥ ।
tan mano ’kurutātmanvī syām iti ।
so ’rcann acarat ।
tasyārcata āpo ’jāyanta ।
arcate vai me kam abhūd iti ।
tad evārkyasyārkatvam ।
kaṃ ha vā asmai bhavati ya evam etad arkyasyārkatvaṃ veda ॥

In the beginning there was nothing (to be perceived) here whatsoever. By Death indeed all this was concealed,--by hunger; for death is hunger. Death (the first being) thought, 'Let me have a body.' Then he moved about, worshipping. From him thus worshipping water was produced. And he said: 'Verily, there appeared to me, while I worshipped (arkate), water (ka).' This is why water is called ar-ka. Surely there is water (or pleasure) for him who thus knows the reason why water is called arka.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)