Kena

The Kena (meaning ‘by whom’) Upanishad, or Kenopanishad has four sections, two of them in verse and the others in prose.

Here are some parts of it:

"The One Power that illumines everything and every one is indivisible. It is the Ear behind the ears, Mind behind the mind, Speech behind speech, Vital Life behind life. The ears cannot hear it; it is what makes the ears hear. The eyes cannot see it; it is what makes the eyes see. You cannot speak about it; it is what makes you speak. The mind cannot imagine it; it is what makes the mind think. It is different from what all we know; yet it is not known either. Those who feel they know Him know Him not. Those who know that anything amenable to the senses is not Brahman, they know it best. When it is known as the innermost witness of all cognitions, whether sensation, perception or thought, then it is known. One who knows thus reaches immortality."

"This is the truth of Brahman in relation to nature and Man. Whether it is the flash of lightning, or the wink of the eyes or the thinking of the mind, the power that is shown is the power of Brahman. For this reason should a man meditate upon Brahman all the time. The sudden Reality that strikes Man as the power behind everything, must be transformed into a permanent Realization."