AITAREYA UPANISHAD · 1.3.8

तन्मनसाजिघृक्षत् तन्नाशक्नोन्मनसा ग्रहीतुं स यद्धैनन्मनसाग्रहैष्यद् ध्यात्वा हैवान्नमत्रप्स्यत् ॥ ८ ॥

tanmanasājighṛkṣat tannāśaknonmanasā grahītuṃ sa yaddhainanmanasāgrahaiṣyad dhyātvā haivānnamatrapsyat ॥ 8 ॥

By the mind He would have seized it, but He could not seize it by the mind. Had He seized it by the mind, then would a man be satisfied by merely thinking food.