Katha Upanishada has six chapters
1. Three Gifts from Death
2. Realizing the Soul
3. The Chariot Analogy
4. This Truly is That
5. The Mystery of God
6. Immortality
In Rigveda nearly 10.135 talks of Yama and a child name Nachiketa (Sanskrit: नचिकेता ,Naciketa) is the child protagonist in an ancient Hindu fable about the nature of the soul and Brahman. The story is told in the Katha Upanishad , though the name has several earlier references. He was taught Self-knowledge, the separation of the human soul (the supreme Self) from the body, by the god of Death, Yama. Nachiketa is noted for his rejection of material desires which are ephemeral, and for his single-minded pursuit of the path of realising Brahman / Moksha i.e. emancipation of the soul from rebirth.
The name Nachiketa,"refers to the quickening Spirit that lies within all things like fire, latent in wood, the spirit that gives." Nachiketa was a son of the sage Vājashravasa (वाजश्रवसः, famed for donations).
Vājashrava, desiring a gift from the gods, started an offering to donate all his possessions. But Nachiketa noticed that he was donating only the cows that were old, barren, blind, or lame; not such as might buy the worshiper a place in Heaven. Nachiketa wanting the best for his father's rite, asked: "I too am yours, to which god will you offer me?". After being pestered thus, vAjashrava answered in a fit of anger, "I give you to Death (Yama)".
So Nachiket went to Yamalok, but the god was out, and he waited three days. When Yama returned, he was sorry to see that a Brahman guest had been waiting so long. He told Nachiketa, "You have waited in my house for three days without hospitality, therefore ask three boons of me". Nachiket first asked for peace for his father and himself. Yama agreed. Next, Nachiketa wished to learn the sacred fire sacrifice, which also Yama elaborated. For his third boon, Nachiketa asked to learn the mystery of what comes after death.
Yama was reluctant on this question; he said that this had been a mystery even to the gods. He asked Nachiketa to ask for some other boon, and offered many material gains.
but Nachiketa replied that material things will last only till the morrow. He who has encountered Death personally, how can he desire wealth? No other boon would do. Yama was secretly pleased with this disciple, and elaborated on the nature of the true Self, which persists beyond death. The key of the realization is that this Self (within each person) is inseparable from Brahman, the supreme spirit, the vital force in the universe. Yama's explanation is a succinct explication of Hindu metaphysics, and focuses on the following points of brahman:
The sound Om! is the syllable of the supreme Brahman
The Self, whose symbol is Om is the same as the omnipresent Brahman. Smaller than the smallest and larger than the largest, the Self is formless and all-pervading.
The goal of the wise is to know this Self.
The Self is like a rider; the horses are the senses, which he guides through the maze of desires.
After death, it is the Self that remains; the Self is immortal.
Mere reading of the scriptures or intellectual learning cannot realize Self.
One must discriminate the self from the body, which is the seat of desire.
Inability to realize Brahman results in one being enmeshed in the cycle of rebirths. Understanding the Self leads to moksha.The Atma, of the size of one's thumb, residing in the body is present always and at all times in the heart of the people. As the minute weeds are removed from the grass, so should the Atma be distinguished and segregated from the body by the use of clear intelligence and steady mind. He is the pure one and the immortal, eternal one.
Thus having lots of conversation with Yama, he learnt the wisdom of the Brahman from Yama, Nachiketa was freed from the cycle of births and Death.
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