From Brihadaranyaka Upanishad:
Śākalya : "How many gods are there?"
Yājñavalkya : "Three hundred and three."
Then he says, "Three thousand and three."
Śākalya : "Is this the answer that you give me to my question, how many gods are there? Three thousand and three; three hundred and three! Have you no other answer to this question?"
Yājñavalkya : There are thirty-three gods.
Śākalya : "All right!" (not satisfied with answer) ...Tell me again properly; how many gods are there?"
Yājñavalkya : "Six are there."
Śākalya : "How many gods are there. Tell me again. Think properly."
Yājñavalkya : "Only three gods are there."
Śākalya : "How many gods are there? Tell again.
Yājñavalkya : "Two gods are there."
Śākalya : "Tell again; how many gods are there?"
Yājñavalkya : "One and a half gods"
(Then he was very much upset)
Śākalya : "What is this you say, one and a half gods. Tell again properly; how many gods are there?"
Yājñavalkya : "One god is there,"
Śākalya : "All these numbers that you have mentioned – three thousand and three, three hundred and three – what are these gods? Give the names of these gods, the deities."
Yājñavalkya : "All these three thousand and all that I mentioned – they are not really gods. They are only manifestations of the thirty-three. The thirty-three are the principal manifestations, and others are only their glories, radiances, manifestations, magnificences or forces, energies, powers."
Śākalya : "But what are these thirty-three?"
Yājñavalkya : "The thirty-three gods are eight Vasus, eleven Rudras, twelve Ādityas, then Indra and Prajāpati – these make thirty-three gods."
Śākalya : "What are these Vasus which are eight in number?"
Yājñavalkya : "Fire is one deity; earth is one deity; air is another; the atmosphere is one deity; the sun is one deity; the heaven is one deity; moon is one deity; the stars are one deity. These constitute eight groups"
Śākalya : "Why do you call them Vasus?"
Yājñavalkya : "Everything is deposited as it were in these constituent principles. Therefore, they are called Vasus."
Śākalya : "Who are the Rudras?"
Yājñavalkya : "The ten senses and the mind make eleven. These are the Rudras."
Śākalya : "What are the twelve Ādityas, the suns?"
Yājñavalkya : "They are twelve forces of the sun, takes away the vitality of people."
Śākalya : "Who is Indra? Who is Prajāpati?"
Yājñavalkya : "The rain cloud can be called Indra. Sacrifice can be called Prajāpati."
Śākalya : "What do you mean by rain cloud?"
Yājñavalkya : "By rain cloud I do not actually mean the cloud, but the lightning which is the embodiment of energy."
