The Kena Upanishad

That which speech does not illumine, but which illumines speech:

know that alone to be the Brahman, not this which people worship here.

That which cannot be thought by mind, but by which, they say, mind is able to think: know that alone to be the Brahman, not this which people worship here.

That which is not seen by the eye, but by which the eye is able to see: know that alone to be the Brahman, not this which people worship here.

That which cannot be heard by the ear, but by which the ear is able to hear: know that alone to be Brahman, not this which people worship here.

That which none breathes with the breath, but by which breath is in–breathed: know that alone to be the Brahman, not this which people worship here.