Chandogya Upanishad is associated with the Kauthuma Shakha of the Sama Veda. It is part of the Chandogya Brahmana, which has ten chapters. The Chandogya Upanishad comprises of eight chapters, and commences on the Om Mantra. Chandogya Upanishad is the part of Chandogya Brahaman that contains ten chapters. The 6th Khanda states about the course after death for the illumined. The arteries of the heart are filled essences of brown, white, blue, yellow and red liquid substances. Verily, the Sun exists as brown, as white, as blue, as yellow and as red. As a main road or bridge with a village at each end, meets both of them so do the rays of the sun meet with both the worlds. They spread from that sun and enter these arteries. From there they enter the sun. When man is so asleep all his senses are devoid of action and his feelings are at rest. He then enters into these arteries. No sin then touches him as he obtains the light of the sun.
When a man becomes weak and suffers from illness the people around him enquire whether he is able to recognise them or not. He is able to recognize them as long as he does not depart from his body. When he quits his body if he is a mere ritualist and ignorant of Brahman he goes upwards with the aid of the rays toward the worlds that he achieved through his meritorious work. If he is aware of the doctrines of the akasa in the lotus of the heart, he then meditates on Om Mantra and achieves entrance into Brahmaloka. However, if he is ignorant of the real Brahman he then attains lower bodies. The person who is aware of the Brahman attains the solar orb soon. It is the door to the World of Brahman for those who are aware of it. It has thus, been said that there are a hundred and one arteries issuing from the heart; one of them penetrates the crown of the head. The man, who departs this life through that artery, secures immortality. The rest of the arteries lead to various transitions.
