The next story belongs to Upakosala Kamalayana, a disciple of this Satyakama, who went to be taught by him and dwelt with him for some time.
Now Satyakama went away on a journey, and the student became very down-hearted; and when the teacher’s wife came and asked him why he was not eating, the boy said, ‘I am too unhappy to eat.’ Then a voice came from the fire he was worshipping, saying ‘This life is Brahman, Brahman is the ether, and Brahman is happiness. Know Brahman.’
‘I know, sir,’ the boy replied, ‘that life is Brahman, but that It is ether and happiness I do not know.’
Then it explained that the two words ether and happiness signified one thing in reality, viz the sentient ether (pure intelligence) that resides in the heart. So, it taught him Brahman as life and as the ether in the heart.
Then the fire taught him, ‘This earth, food, fire, and sun whom you worship, are forms of Brahman. The person that is seen in the sun, I am He. He who knows this and meditates on Him, all his sins vanish and he has long life and becomes happy. He who lives in the cardinal points, the moon, the stars, and the water, I am He. He who lives in this life, the ether, the heavens, and the lightning, I am He.’ Here too we see the same idea of practical religion. The things which they were worshipping, such as the fire, the sun, the moon, and so forth, and the voice with which they were familiar, form the subject of the stories which explain them and give them a higher meaning.
And this is the real, practical side of Vedanta. It does not destroy the world, but it explains it; it does not destroy the person, but explains him; it does not destroy the individuality, but explains it by showing the real individuality. It does not show that this world is vain and does not exist, but it says, ‘Understand what this world is, so that it may not hurt you.’
The voice did not say to Upakosala that the fire which he was worshipping, or the sun, or the moon, or the lightning, or anything else, was all wrong, but it showed him that the same spirit which was inside the sun, and the moon, and lightning, and the fire, and the earth, was in him, so that everything became transformed, as it were, in the eyes of Upakosala. The fire which was merely a material fire before, in which to make oblations, assumed a new aspect and became the Lord. The earth became transformed, life became transformed, the sun, the moon, the stars, the lightning, everything became transformed and deified. Their real nature was known.
Source: The Complete Works of Swami Vivekananda/Volume 2/Practical Vedanta and other lectures/Practical Vedanta: Part II