CHĀNDOGYA UPANISHAD · 6.1.6

यथा सोम्यैकेन नखनिकृन्तनेन सर्वं कार्ष्णायसं विज्ञातं स्यात् ।
वाचारम्भणं विकारो नामधेयं कृष्णायसम् इत्य् एव सत्यम् ।
एवं सोम्य स आदेशो भवतीति ॥

yathā somyaikena nakhanikṛntanena sarvaṃ kārṣṇāyasaṃ vijñātaṃ syāt ।
vācārambhaṇaṃ vikāro nāmadheyaṃ kṛṣṇāyasam ity eva satyam ।
evaṃ somya sa ādeśo bhavatīti ॥

'And as, my dear, by one pair of nail-scissors all that is made of iron (kârshnâyasam) is known, the difference being only a name, arising from speech, but the truth being that all is iron,--thus, my dear, is that instruction.'

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