Story from Upanishad

There is a story from Upnanishads about shwetketu. Shwetketu had gone to his gurukul to gain knowledge. After twelve years when he returned, He did not do pranaam or touch his father's feet. He thought that he has more knowledge than hus father. He saw his father was sitting in yagyashala. The father observed his son's style of talking, he did not appreciate it. He did not touch his father's feet nor he did any pranaam to him.
Father said "Oh! I sent you to gurukul to collect all dirt. What have you learnt? Only about bricks and stones. Can knowledge impart Ego? You have just collected dirt.
Knowledge teaches you politeness. It is like a tree which bends low when it starts bearing fruits. The father then asked Swetketu "You have completely attained knowledge".
He replied "Yes, father. I remember everything, you can ask me from anywhere".

The father asked"Did you learn about the One and knowing that Only One you don't have to know anything'.

The son promptly replied "There is no such knowledge to know about The One and if it is there then my Guruji(teacher) may not be knowing as he did not teach me about The Only One".

The father told his son to go back to Gurukul. He said "Being a Brahmin's son does not mean you become a Brahmin, the one who knows about Brahma Vidhya is a Brahmin. Go and ask your Guru about it.

Shwetketu went back to Gurukul and asked his Guru whether there is any vidhya which teaches about The Only One. The Guru replied "Yes, there is." The boy said why did not you tell me about this.

Guru said "I answered all your queries, but you never wanted to know The Brahm Vidhya. He requested his Guru and told him to tell about the Only One.

The Guru answers "Tatvam Aasi" Oho ! That is You, my son. Know thyself, know your atman. know yourself from within, your atma, your trueself.

"Atma Ka Gyan" Knowledge about Self. After hearing this, Swetketu immediately gained the knowledge. His Gurukul vidhya which his father wanted was complete. Observe and look at Atma, search for truth and God. Look for peace. In one instance and one incident can open our eyes and attain knowledge.