Kena Upanishad 1.4-8: 'What cannot be spoken with words, but that whereby words are spoken: Know that alone to be Brahman [...] What cannot be thought with the mind, but that whereby the mind can think: Know that alone to be Brahman [...] What cannot be seen with the eye, but that whereby the eye can see: Know that alone to be Brahman [...] What cannot be heard with the ear, but that whereby the ear can hear: Know that alone to be Brahman [...] What cannot be indrawn with breath, but that whereby breath is indrawn: Know that alone to be Brahman, the Spirit; and not what people here adore.'