This prayer is uttered with a view to removing all faults incurred through lapses resulting from inadvertence during the course of acquiring or imparting the knowledge, through the dialogue between a realized soul acting as the Seer, Teacher, and a sincere seeker of Truth who approaches Him as a disciple. In Katha Upanishad, the teacher is Yama - The God of Death Himself - and the student is a young Nachiketa in his teens. This Upanishad is one of the most popular Upanishads for its simplicity and clarity, and consists altogether of 120 verses.

As the story goes, Vajashrava, Nachiketa’s father, decided to acquire the fruits of a special sacrificial ritual -Viswajit Yagna in which the performer had to give away all his precious possessions. Cows were regarded as valuable possessions in those days, and hence Vajashrava decided to donate all his cows to Brahmins. Nachiketa was in his teens, and was observing the sacrificial ritual with innocent interest. However, he was surprised to notice that his father was giving away only old and disabled cows, cows ‘who had given their milk for the last time and which were not capable of bearing calves’.

This insincerity of his father who was committing a grave sin knowingly or unknowingly by sacrificing such cows betrayed, a lack of faith in the reality of divinities. But Nachiketa had faith in the reality of the divinities and was worried about the harmful consequences of a ritual performed without faith and sincerity. Nachiketa, in order to dissuade his father from engaging in further mean acts, asked, "O father, to whom have you decided to give me away?" (After all, the son was also one of the precious possessions!) The father did not take any notice of what appeared to be a ‘childish’ question, but Nachiketa was insistent. He repeated the question thrice when the irritated father said, "All right, O Nachiketa, I give you to Death."

Thus ordained, young Nachiketa went to the kingdom of Yama - The God of Death - where he waited for his return from his duties. On his return, Yama was told about the ‘Brahmin boy waiting for him for three days without food or water’. Yama praised the sincerity of Nachiketa but also felt grieved that he was responsible for keeping a boy waiting for him. Therefore, he granted three boons to Nachiketa one each for a day of waiting.

"O God of Death, of the three boons you have offered me, I ask for the first to the effect that my father may become freed from anxiety about me and he may recognize me and talk to me when freed by you." The boon was granted. As the next boon Nachiketa asked for granting him the knowledge of the means to attain higher life in the heaven and immortality. There is a dialogue between Yama and the boy about the primordial Fire and sacrificial rituals to attain heavenly life. Yama tells him about the methods and ways of performing these Yagnas etc. that will help one to attain heavenly pleasures.

The Third Boon concerns the core of Katha Upanished.

Nachiketa wants to know: "This doubt that arises, consequent on the death of a man - some saying ‘It (The SELF) exists’, and others saying ‘It (The SELF) does not exist’. I would like to know this, under your instruction, O God of Death, what is the Truth."

Nachiketa had asked for the ultimate knowledge. Yama tries to dissuade the young boy from going into these subtle questions and exhorts Nachiketa to ask for health, life, riches, jewels, and enjoyment. But Nachiketa argues that all worldly treasures and heavenly pleasures come to an end sooner or later.

Nachiketa says, "O God of Death, ephemeral are these, and they waste away the vigour of all the organs that a man has. All life without exception, is short indeed. Let the vehicles be yours alone; let the dances and songs be yours. "O God of Death, you have promised me the third boon."

Seeing the determination, faith, sincerity, and perseverance of Nachiketa, seeing him to be the perfect disciple, the God of Death agrees to tell him about the Ultimate Reality: Brahman or Atman. Yama says, "The good is different from the unpleasant. He who selects the pleasant over the good fails to reach the true goal."

"The intelligent one selects the electable in preference to the delectable i.e, the good over the pleasant; the non-intelligent one selects the delectable for the sake of growth and protection of the body, etc."

"O Nachiketa, you, have discarded, after consideration, all the desirable things that are delightful. You have not accepted this path of wealth in which many a man comes to grief."

"Living in the midst of ignorance and considering themselves intelligent and enlightened, the senseless people go round and round, following crooked courses, just like the blind led by the blind."

"This wisdom that you have, O Nachiketa, which leads to sound knowledge, is not to be attained through argumentation. You are, endowed with true resolution. May every questioner be like you, O Nachiketa!"

And as Yama goes on elaborating the subtlety and nuances of means and methods to achieve that transcendental state, consciousness of Nachiketa also is getting established in that altered state to experience those Truths.

"The intelligent man gives up joy and sorrow by meditation on the Inner Self and thereby meditating on the ancient effulgent one who is insrcutable, lodged inaccessibly, located in the intellect, and seated in the midst of the body." (Katho. II:12)

" The intelligent Self is neither born nor does It die. It did not originate from anything, nor did anything originate from It. It is birthless, eternal, undecaying, and ancient. It is not injured even when the body is destroyed." (II:18) "The Self that is subtler than the subtlest, and greater than the greatest, is lodged in the heart of every creature. A desireless man sees that glory of the Self through the serenity of the mind and the organs and thereby he becomes free from sorrow." (II: 20)

And so Nachiketa gets established into highest state of bliss where ‘knowledge of Brahman becomes a fact of direct experience’.