Upanishad in Sanskrit means ‘sitting down near or at the feet of’ (referring to sitting down near the spiritual teacher or at the feet of Truth). The Upanishad texts are referred to as Vedanta or the last or final parts of the Vedas because they contain the most profound wisdom of the Vedas.
The Upanishads have not only been revered in India for the highest wisdom that they embody, but in recent centuries have even impacted many Western scholars and thinkers. The famous Danish physicist and Nobel Laureate Niels Bohr (1885-1962) said, “I go into the Upanishads to ask questions.” Bohr as well as other physicists like Erwin Schrödinger and Werner Heisenberg were avid readers of the Vedic texts and observed that their experiments in quantum physics were consistent with what they had read in the Vedas.1 The 19th century German philosopher Arthur Schopenhauer was so impressed by the Upanishads, that he called them “the production of the highest human wisdom”.2
Kena in Sanskrit means ‘by what or by whom directed’. The Kena Upanishad (or Kenopanishat) begins with enquiry into the Self, Brahman or the Absolute. The method of Self-enquiry has been used since ancient times as a way to discover the reality of the Self. Perhaps most well-known in our times is the guidance of Sri Ramana Maharshi towards the enquiry ‘Who Am I’. These enquiries and pointings are meant to be contemplated sincerely and with perseverance. They are the most direct way of attaining liberation or freedom.
Kena Upanishad3
1. By whom willed and directed does the mind light on its subjects? By whom commanded does prana, the first, move? By whose will do men speak this speech? What Intelligence directs the eye and the ear?
2. It is the ear of the ear, mind of the mind, tongue of the tongue, and also life of the life and eye of the eye. Being disabused of the false notion, the wise, having left this body, become immortal.
3. The eye does not go there, nor speech, nor mind. We do not know That. We do not know how to instruct one about It. It is distinct from the known and above the unknown. We have heard it so stated by preceptors who taught us that.
4. What speech does not enlighten, but what enlightens speech, know that alone to be the Brahman, not this which (people) here worship.
5. What one cannot think with the mind, but by which they say the mind is made to think, know That alone to be the Brahman, not this which (people) here worship.
6. What cannot be seen by the eye, but by which the eyes are able to see. That alone know thou to be the Brahman; not this which (people) here worship.
7. What cannot be heard with the ear, but by which the ears are able to hear, That alone know thou to be the Brahman; not this which (people) here worship.
8. What none breathes with the breath, but by which breath is in-breathed, That alone know thou to be the Brahman; not this which (people) here worship.
(1) http://www.krishnapath.org/quantum-physics-came-from-the-vedas-schrodinger-einstein-and-tesla-were-all-vedantists/
(2) https://en.wikipedia.org/wiki/Kena_Upanishad
(3) Translation sourced from ‘The Kena Upanishad with Shankara’s Commentary’ See more: http://www.wisdomlib.org/hinduism/book/kena-upanishad-shankara-bhashya
