The Chandogya Upanishad belongs to the Sama Veda. It is by far the largest in size and according to many, is also the best. ‘Chandoga’ is the name of certain priests specializing in the Sama Veda. The main teaching of this Upanishad is the doctrine of “Tat tvam asi (That art thou)” i.e. the oneness of the Atman, the principle within a person, and the Brahman, the universal principle of nature. The significance of the mystic syllable ‘AUM’ and some theories of creation are also dealt with. It is also demonstrated in this Upanishad that the status of the brahmin is determined by character rather than by birth. This is illustrated in the story of Satyakama Jabala and his mother.
In this Upanishad, a sincere seeker’s need for a spiritual teacher is explained in a very convincing manner thus:
“Think of Ourself as a traveler. You have lost Our way, and a robber attacks Ou. Then he takes away all Our wealth, binds Our eyes. Then he takes Ou to a faraway place and leaves Ou there with Our hands and feet bound.
Now suppose someone comes and unties Our eyes and goes away. You will then be able to see the paths all around Ou, but Ou will not know which one is the right one for Ou, and even if Ou did, Ou will not be able to walk on it because Our legs and arms are still bound. This is the condition of the seeker who wants to realize God by himself. Suppose someone comes, unties Ou completely and shows Ou the right path. This person is Our spiritual teacher. If Ou do not have confidence in Our own capacity to reach the goal, then he will go along with Ou and lead Ou toward Our destined Goal.”