Experience is the best teacher.

One day, Brighu, the son of Varuna approached his father and asked him: "Father! Will you enlighten me about Brahman?" Sage Varuna replied endearingly: "Son, none can enlighten anyone on Brahman. One has to experience through meditation. Go and do meditation and carry on self-enquiry. I bless you."

Brighu went into a forest and sat for meditation. He used to carry on self-enquiry too. He used to contemplate on several questions related to the spiritual world. One day, he thought: 'What is the most essential thing that is necessary for the existence of all living beings in general and man in particular? It must be food', he decided. Man lives, grows and works only because of food, the most essential thing for life is food, so food is Brahman." He ran to his father and said: "Father, I know what is Brahman. Food is Brahman." Varuna replied with a smile: "No, my son, food is not Brahman. Go and meditate."
Brighu went to the forest and continued his tapas for some more time. One day he thought, 'food may be essential, but unless there is energy, how can the food be digested? What is that energy? It must be prana (vital air) so prana is Brahman.' So, he went to his father and said: "Father, I know what is Brahman, Prana is Brahman." Varuna replied: "No, my son, go and meditate for some more days."
Brighu obeyed his father's command. He continued his meditation. One day he thought, 'Food is essential, prana is essential, but what is more essential? Unless one has desire to live and to eat, of what avail is food and prana? The seat of desire is mind. So Manas is Brahman' he decided. Brighu reported about his discovery and said: "Father, Manas is Brahman." Varuna smiled and said: "Son, no, Manas is not Brahman. Go and do tapas for some more days."

Brighu continued his meditation. One day he thought 'Food is essential, prana is essential, manas is also essential, but what is still more essential? Unless one is able to distinguish and discriminate between good and evil, of what use is this life? What is the seat of this discriminating faculty? It is intellect, vijnan.' So vijnan is Brahman", he decided. Brighu went and told his father: "Father, vijnan is Brahman". Varuna once again said: "Son, no, vijnan is not Brahman. Go and do tapas for some more days."

Brighu once again continued to do tapas. One day he thought, 'Food gives strength, parna energises, manas causes desires, and vijnan endows man with discrimination (viveka). But, I must find out what is the ultimate goal of man's life. I have to experience it'. Having thus resolved, he went into deep meditation again.

One day, he experienced an ineffable joy and he sat utterly unconscious of the outside world. That day, Varuna came to the forest in search of his son. He was happy to see his son in samadhi. From the effulgence which shone on Brighu's face, he knew that his son had realised that 'Bliss is Brahman'.

In the upanishadic age, parents and preceptors used to encourage their pupils to ask questions, yet they would not give them immediate answers. They would advise them to carry on self enquiry and find out the answers for themselves.

Experience is the best teacher.