The God of Death reveals the mysteries of the one true Self in all.
The following is a translation of the Katha Upanishad from The Principal Upanishads by S. Radhakrishnan. This Upanishad is found within the Yajurveda and consists of two chapters, each divided into three sections. It consists mainly of the story of young Nachiketa and his philosophical conversations with Lord Yama, God of Death. The following verses, 4 to 18, are drawn from section three of chapter two, and have been lightly edited for clarity.
4 Lord Yama: “If one is able to perceive Him before the body falls away, one would be freed from suffering. If not, he becomes fit for another birth in the created worlds.”
5 “As in a mirror, so It is seen in the soul; as in a dream, so It is seen in the world of the ancestors; It is seen in the world of the gandharvas as an object is seen in water; in the world of Brahma It is seen as shade and light.
6 “Knowing the separate nature of the senses, which spring from the subtle elements, and knowing also that their rising and setting are separate, the wise man does not grieve.
7 “Beyond the senses is the mind; above the mind is its essence; beyond that essence is the great Self; beyond the great Self is the unmanifest.
8 “Beyond the unmanifest is the One—all-pervading and without any blemish whatsoever.—Whom by knowing, a man is liberated and gains eternity.
9 “Not within the field of vision stands this form. No one soever sees Him with the eye. By heart, by thought, by mind apprehended, they who know Him become immortal.
10 “When the five senses and their knowledge, together with the mind, cease their activities, and when the intellect itself does not stir, that, they say, is the highest state.
11 “This, they consider to be yoga, the steady control of the senses. Then one becomes undistracted, for yoga comes and goes, due to the mind’s fluctuation.
12 “Not by speech, not by mind, not by sight can He be apprehended. How can He be comprehended except by him who says, ‘He is.’
13 “He should be apprehended simply as existence, but also in His real nature (non-existence). When He is apprehended as existence, His real nature becomes clear.
14 “When all desires that dwell within the human heart are cast away, then a mortal becomes immortal; and even here he attains to Brahman.
15 When all the knots that fetter the heart are cut asunder, then a mortal becomes immortal. Thus far is the teaching.
16 “A hundred and one are the pathways of the heart; one of them leads up to the crown of the head. Going upward through that, one becomes immortal. The others serve for going in a variety of other directions.
17 “Abiding always in the heart is the thumb-sized, inner self. Him one should draw out with firmness from the body, as the wind from a reed. Him one should know as the pure, the immortal.”
18 Then Nachiketa, having gained this knowledge, declared by Death and the whole law of yoga, attained Brahman and became freed from passion and death. And so may any other who knows this knowledge of the Self.