Kausitaki Upanishad belongs to Kausitaki branch of Rig Veda. This Upanishad is a part of Kaushitaki Aranyaka that is again a part of the Kaushitaki Brahmana. Kaushitaki Aranyaka comprises 15 chapters. Here the sage Kaushitaki taught about the importance of Prana, the breathing spirit. Prana here is the real self and is immortal and ageless. In the first chapter of Kausitaki Upanishad Chitra Gargyayani explains about Brahma and the real self to the priest Arni.
According to the story of the first chapter once Chitra Gargyayani, the son of Gangya wished to offer a sacrifice and hence chose Arnni as his priest. Aruni sent his son Svetaketu to perform the sacrifice. When he sat for the sacrifice, Gargyayani asked him is there any abode in the world where he can set him. He however, replied that as he was unaware he needs to consult his father. His father too was unaware of the answer. Hence he thought of their Vedic studies in his residence and get the required information. Then, with fuel, in hand Aruni returned to Chitra Gargyayani and asked him to accept him as his pupil. He told Chitra that as he was worthy of sacred knowledge he shall reply to his questions.
Chitra Gargyayani then replied that whoever departs from the world go to the moon.
In the earlier half of the lunar month the moon flourished on their breath and then in the later half, it causes them to be reproduced. The moon here is the door of the heavenly world. He who accepts it is set free but who rejects it rains down. Later he becomes a worm or an insect or a fish, or a bird, or a lion, or a boar, or a snake or a tiger or a person or some other in this or that condition according to his deeds and knowledge. When the sage asked who he was, Chitra replied that seeds were collected from the wise season ordaining moon and placed in a man. Later the man placed it in a woman, from whom he was born. He then said that one needs to know the knowledge that is truth and to know the knowledge that is against the truth.
He further says that having reached the divine road he goes into the world of Agni (fire), then to the world of Vayu (air), then to the world of Varuna, then to the world of Indra, then to the world of Prajapatit and then to the world of Brahma. The world of Brahma has a lake of Ara or enemies, the sacrifice-destroying moments; the Age-less river ; the Ilya tree; the Salajya city; the impregnable Palace; the door keepers Indra and Prajapati; Brahma`s hall Vibhu; his throne Vichakshana, his coach of Amitaujas, the mothers, the nurses, the nymphs and the rivers. The person who is well aware of these advances forth.
Five hundred Apsarasas go to meet him, with fruits, perfumes, garlands, garments, aromatics. They adorn him with the ornaments of Lord Brahma. He comes to the lake of enemies, and crosses it by his mind. Those who only know the present sink. Just as one driving swiftly in a chariot looks down on the two wheels revolving, so too he looks down on day and night, on good deeds and bad deeds, and on all the pairs ; he, free from good deeds, free from bad deeds, knowing Brahma, advances toward Brahma. Just as one driving a chariot looks at the wheel of the chariot, he looks upon day and night; upon good deeds and evil deeds and upon of pairs of opposites. Thus, the knower of Brahman, devoid of good deeds, devoid of evil deeds, goes on to Brahman.
It is explained that Self is Truth; it is the Self of all and is Brahman. He is the real one. He is thus expressed by the word satyam.
