Chandogya Upanishad 6.41

तस्य क्व मूलँ स्यादन्यत्रान्नादेवमेव खलु सोम्यान्नेन शुङ्गेनापो मूलमन्विच्छाद्भिः सोम्य शुङ्गेन तेजोमूलमन्विच्छ तेजसा सोम्य शुङ्गेन सन्मूलमन्विच्छ सन्मूलाः सोम्येमाः सर्वाः प्रजाः सदायतनाः सत्प्रतिष्ठाः ॥ ४ ॥

6.8.4 — tasya kva mulan syadanyatrannadevameva khalu somyannena shungenapo mulamanvichchhadbhih somya shungena tejomulamanvichchha tejasa somya shungena sanmulamanvichchha sanmulah somyemah sarvah prajah sadayatanah satpratishthah || 4 ||

And where could its root be except in food (earth)? And in the same manner, my son, as ​food (earth) too is an offshoot, seek after its root, viz. water. And as water too is an offshoot, seek after its root, viz. fire. And as fire too is an offshoot, seek after its root, viz. the True. Yes, all these creatures, my son, have their root in the True, they dwell in the True, they rest in the True.

'इसका मूल कहाँ होगा, अन्न के अतिरिक्त? इसी प्रकार हे सौम्य, अन्न रूपी शाखा का मूल जल में खोज; जल रूपी शाखा का मूल तेज में खोज; तेज रूपी शाखा का मूल सत् में खोज। हे सौम्य, ये समस्त प्रजाएँ सत्-मूल हैं, सत्-आयतन हैं, सत्-प्रतिष्ठ हैं।'