BṚHADĀRAṆYAKA UPANISHAD · 4.3.2

याज्ञवल्क्य किंज्योतिर् अयं पुरुष इति ।
आदित्यज्योतिः सम्राड् इति होवाच ।
आदित्येनैवायं ज्योतिषास्ते पल्ययते कर्म कुरुते विपल्येतीति ।
एवम् एवैतद् याज्ञवल्क्य ॥

yājñavalkya kiṃjyotir ayaṃ puruṣa iti ।
ādityajyotiḥ samrāḍ iti hovāca ।
ādityenaivāyaṃ jyotiṣāste palyayate karma kurute vipalyetīti ।
evam evaitad yājñavalkya ॥

'Yâgñavalkya,' he said, 'what is the light of man?' Yâgñavalkya replied: 'The sun, O King; for, having the sun alone for his light, man sits, moves about, does his work, and returns.' Ganaka Vaideha said: 'So indeed it is, O Yâgñavalkya.'

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