The Kena Upanishad begins with a series of questions that progressively strip away all ordinary frameworks for understanding the divine: what directs the eye to see, the ear to hear, the speech to speak, the mind to think, the breath to breathe? The questions are not rhetorical — they are genuine philosophical enquiries into the source of consciousness. The answer the Upanishad gives is not "Brahman directs all these" but something more precise: Brahman is not the object of any of these activities (eye, ear, mind) — it is that which enables them. Brahman is the eye of the eye, the ear of the ear, the mind of the mind.
The mythological section — Brahman humbles the gods
The Kena's second section (Parts 3-4) shifts abruptly from philosophy to mythology. The gods — Agni, Vayu, Indra — have just defeated the demons in battle and are boasting of their power. A mysterious Yaksha (spirit) appears before them. Each god approaches and claims to be omnipotent: Agni says he can burn everything; Vayu says he can blow everything away. The Yaksha places a blade of grass before each and challenges them to act on it. They cannot. Indra approaches — and the Yaksha vanishes, replaced by the beautiful Uma Haimavati (the daughter of the Himalayas, Shiva's consort). Uma reveals: the mysterious Yaksha was Brahman itself. The mythological point: the gods' power derives from Brahman — they mistook Brahman's victory for their own. Source: Olivelle (1998).
Shankara's commentary — the most important philosophical reading
Shankara's commentary on the Kena is one of his most philosophically refined. His analysis of the "eye of the eye" passage: the eye sees objects, but what sees the eye? The mind perceives the eye's activity, but what perceives the mind? Each faculty of knowing is itself an object of a higher faculty — until we reach a faculty that cannot itself be objectified. That is the Atman/Brahman — the pure witness that enables all knowing but is never itself an object of knowing. Shankara's argument: this pure witness-consciousness is what the Kena calls "the ear of the ear." Source: Gambhirananda (2004).
Uma Haimavati — Brahman revealed through the Goddess
The appearance of Uma Haimavati (the daughter of Himavat — Shiva's consort) as the revealer of Brahman in the Kena's mythological section is theologically significant: it is through the Goddess's instruction that Indra learns what Brahman is. This makes the Kena one of the few Upanishads where a female figure serves as the theological teacher — and has been noted by Shakta theologians as evidence for the Goddess's role as the revealer of ultimate truth. Source: Olivelle (1998); Coburn (1988).
Olivelle (1998). Gambhirananda (2004). Coburn (1988).
The Kena and the problem of self-referential knowledge
The Kena's paradox of knowing ("known to those who do not know; unknown to those who know") is one of the earliest articulations in world philosophy of the problem of self-referential consciousness. The argument: any attempt to make Brahman/Atman an object of knowledge misses it, because Brahman is the subject that does the knowing, not an object that is known. This is structurally similar to arguments made in later Western philosophy (Kant on the thing-in-itself, Wittgenstein on the limits of language, Husserl on the transcendental ego) — though the Kena's conclusion is different from all of these. The Kena does not conclude that Brahman is unknowable — it concludes that Brahman is known in the recognition that ordinary objectified knowing cannot grasp it. This recognition is itself the knowing. Source: Gambhirananda (2004); Halbfass (1988).