CHĀNDOGYA UPANISHAD · 6.4.7

यद् व् अविज्ञातम् इवाभूद् इत्य् एतासाम् एव देवतानां समास इति तद् विदां चक्रुः ।
यथा नु खलु सोम्येमास् तिस्रो देवताः पुरुषं प्राप्य त्रिवृत् त्रिवृद् एकैका भवति तन् मे विजानीहीति ॥

yad v avijñātam ivābhūd ity etāsām eva devatānāṃ samāsa iti tad vidāṃ cakruḥ ।
yathā nu khalu somyemās tisro devatāḥ puruṣaṃ prāpya trivṛt trivṛd ekaikā bhavati tan me vijānīhīti ॥

'Whatever they thought was altogether unknown, they knew was some combination of those three beings (devatâ). 'Now learn from me, my friend, how those three beings, when they reach man, become each of them tripartite.

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