CHĀNDOGYA UPANISHAD · 8.12.4

अथ यत्रैतद् आकाशम् अनुविषण्णं चक्षुः स चाक्षुषः पुरुषो दर्शनाय चक्षुः ।
अथ यो वेदेदं जिघ्राणीति स आत्मा गन्धाय घ्राणम् ।
अथ यो वेदेदम् अभिव्याहराणीति स आत्मा अभिव्याहाराय वाक् ।
अथ यो वेदेदं शृण्वानीति स आत्मा श्रवणाय श्रोत्रम् ॥

atha yatraitad ākāśam anuviṣaṇṇaṃ cakṣuḥ sa cākṣuṣaḥ puruṣo darśanāya cakṣuḥ ।
atha yo vededaṃ jighrāṇīti sa ātmā gandhāya ghrāṇam ।
atha yo vededam abhivyāharāṇīti sa ātmā abhivyāhārāya vāk ।
atha yo vededaṃ śṛṇvānīti sa ātmā śravaṇāya śrotram ॥

'Now where the sight has entered into the void (the open space, the black pupil of the eye), there is the person of the eye, the eye itself is the instrument of seeing. He who knows, let me smell this, he is the Self, the nose is the instrument of smelling. He who knows, let me say this, he is the Self, the tongue is the instrument of saying. He who knows, let me hear this, he is the Self, the ear is the instrument of hearing.

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