CHĀNDOGYA UPANISHAD · 6.8.5

अथ यत्रैतत् पुरुषः पिपासति नाम तेज एव तत् पीतं नयते ।
तद् यथा गोनायो ऽश्वनायः पुरुषनाय इत्य् एवं तत् तेज आचष्ट उदन्येति ।
तत्रैतद् एव शुङ्गम् उत्पतितं सोम्य विजानीहि ।
नेदम् अमूलं भविष्यतीति ॥

atha yatraitat puruṣaḥ pipāsati nāma teja eva tat pītaṃ nayate ।
tad yathā gonāyo ’śvanāyaḥ puruṣanāya ity evaṃ tat teja ācaṣṭa udanyeti ।
tatraitad eva śuṅgam utpatitaṃ somya vijānīhi ।
nedam amūlaṃ bhaviṣyatīti ॥

'When a man is thus said to be thirsty, fire carries away what has been drunk by him. Therefore as they speak of a cow-leader (go-nâya), of a horse-leader (asva-nâya), of a man-leader (purusha-nâya), so they call fire udanyâ, thirst, i. e. water-leader. Thus (by water digested &c.), my son, know this offshoot (the body) to be brought forth: this (body) could not be without a root (cause).

F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)