Katha Upanishad consists of 120 verses, is one of the most popular Upanishads known for its simplicity and clarity in making the subject matter regarding the Highest Truth easily understandable. The Fifth Chapter of Katha Upanishad has 15 verses where Lord Yama explains about Brahman to Nachiketa.

. 1st - 5th Verse
Yama tells Nachiketa that by meditating on the Atma that is immortal one gets relieved from all pains and sorrows. He is the one that exists without any blemishes and resides city of eleven gates i.e. the human body with eleven pores in different places. Upon realising the Supreme Being he becomes a wise man and gets rid off the bonds of birth and death. He is the sun who travels in the pure, clear sky; He fills up the entire space of the universe; He is the fire where yagna is performed; He is the guest at people`s houses; He dwells in all; He is in the best in Devas; He is in the sky; He is the truth; He is visible in various forms in the water, earth, yagna and in the mountains. He is present everywhere. He is the force that moves the prana upwards and also brings down the apaana. He resides in the centre of the body in the small form. If this Atma leaves the body nothing else would remain. A living being just does not exist on the prana, the inward breath and apaana, the outward breath. He exists on the Atma that is the source of these forms of breath.

6th - 10th Verse
Yama now explains Nachiketa about the state and the whereabouts of the Jiva after death. He said that there are some who enter the womb for assuming a body. Others become plants or other stationary objects. All these are a result of one`s actions, thoughts and knowledge. The Purusha remains awake in even the one who is sleeping and engaged in fulfilling materialistic desires. He is the pure; He is the Brahman; He is called as the eternal and immortal. Within him the whole world resides. Like the fire and the air that enters different forms of worldly objects assumes the shapes of various objects, the Atma also upon entering different bodies takes various forms. It however, remains one and exits beyond all objects.

11th - 15th Verse
As the one sun, the eye of the whole world, is not attacked by the defects of the eye or of external things, so the soul or Atma, as the inner soul of all beings, is not sullied by the unhappiness of the world. Knowledgeable men who regard the Atma as the Supreme Divine and which multiplies its single form into various, can enjoy limitless joy. A wise man who realises that the Atma is the only stable thing in this transient world, is all knowledgeable of all the beings, stands as one, grants the desires of all, and resides within all, attains eternal peace. Neither the sun nor the moon, nor the stars and fire shine. They all shine only by depending on Him who itself is self-illuminating. It is only through His light that other things can be seen and understood.