Root up and branches down is this ancient asvattha tree, that (its source) is pure. That is Brahman and that alone is called immortal. On that, do all worlds depend and none passes beyond that. This verily is that.
All this universe of motion moves in the Prana, and from the Prana also it proceeded; a mighty terror is He, yea, a thunderbolt uplifted. Who know Him are the immortals.
It is because of its fear that the fire is kindled, it is because of its fear that the sun shines, it is because of its fear that Indra, and Vayu, and Death move on their respective paths.
If, before leaving the body in this human world, you can realize Him, then you become fit to assume body in the various worlds created by Him.
In the soul, one sees the Supreme Lord as in a mirror, but in the Pitraloka one sees the Self, and in the Gandharva world one sees Him as one sees the surface of an object in water. But in Brahmaloka it appears like light and shadow.
Knowing the separateness of the senses, their rising and setting, and their separate origin, the patient removes sorrow and grief.
The mind is above the senses, and higher than the mind is the intellect, higher than the intellect is the great Self, and higher than that essence, the Unmanifested.
Better than the unmanifested is the Purusha, who is all-pervading, and of that unique one there is no sign, no sign. By attaining its knowledge, the creature becomes free, and gains immortality.
He does not conceal His body (His form) within the reach of sight, nor does any man see it with the eyes, but to the heart, mind, and supermind, it is manifested. Those who know him become immortal.
When the five senses become calm and still, and the mind also becomes still with them, and the processes of the intellect also become still, then that is the highest state, the ultimate movement, so say the sages.
That steady state, in which the senses are subordinate to the state of perception of the mind, is called yoga. In that state, man becomes completely conscious-aware. Because yoga is both the origin of substances, and the rhythm.
Not by speech, not by mind, not by the eye, can he be attained; except in his case who says, "He is", how can that be known.
Realization of him (sense of existence), "he", and his "tattvabhava", should be obtained in both forms. But when humans come to know it as it really is, then its essence is revealed to that person.
When the hold of every desire, dependent on the heart of a man, becomes loose, then this mortal (human) becomes immortal. It is here, in this human body, that he relishes the Brahman.
When here, in this very human life, the heart glands are disintegrated, then this mortal (human) becomes immortal. This is the whole education of Shrutis, it is discipline.
A hundred and one are the nerves of the heart. Of them, one has gone out piercing the head; going up through it, one attains immortality; others at the time of death lead different ways.
Purusha, the soul, who is only a thumb, is always seated in the hearts of the living beings. He should be patiently separated from his body in the same way as one separates his seashell from an ocean. You know him to be radiant, immortal, yes, know him to be radiant (pure), immortal.
In this way Nachiketa, in the form of death, received this Brahmavidya, told by the Guru. In the same way he came to know the whole yoga method. After that he attained Brahma, and he became pure and deathless. Whoever else gets this spiritual knowledge, he will also become like him.
Let Him protect us both; let us exert together may what we study be well studied; may we not hate.