How to tell

There is nothing that does not come from him.
Of everything he is the inmost Self.
He is the truth; he is the Self supreme.
You are that, Shvetaketu; you are that."

"Please, Father, tell me more about this Self."

"Yes, dear one, I will," Uddalaka said.
"Strike at the root of a tree; it would bleed
But still live. Strike again at the top;
It would bleed but still live. The Self as life
Supports the tree, which stands firm and enjoys
The nourishment it receives.
If the Self leaves one branch, that branch withers.
If it leaves a second, that too withers.
If it leaves a third, that again withers.
Let it leave the whole tree, the whole tree dies.
Just so, dear one, when death comes and the Self
Departs from the body, the body dies.
But the Self dies not.

"There is nothing that does not come from him.
Of everything he is the inmost Self.
He is the truth; he is the Self supreme.
You are that Shvetaketu; you are that."

"Please Father, tell me more about this Self."
"Yes, dear one, I will," Uddalaka said.
"Bring me a fruit from the nyagrodha tree."

"Here it is, Sir."

"Break it. What do you see?"

"Nothing at all."

"That hidden essence you do not see, dear one,
From that a whole nyagrodha tree will grow.
There is nothing that does not come from him.
Of everything he is the inmost Self.
He is the truth; he is the Self supreme.
You are that, Shvetaketu; you are that."

"Please, Father, tell me more about this Self."

"Yes dear one, I will," Uddalaka said.
"Place this salt in water and bring it here
Tomorrow morning." The boy did.
"Where is that salt?" his father asked.

"I do not see it."

"Sip here. How does it taste?"

"Salty, Father."

":And here? And there?"

"I taste salt everywhere."

"It is everywhere, though we see it not.
Just so, dear one, the Self is everywhere,
Within all things although we see him not.
There is nothing that does not come from him.
Of everything he is the inmost Self.
He is the truth; he is the Self supreme.
You are that, Shvetaketu; you are that."

"Please, Father, tell me more about this Self."

"Yes, dear one, I will," Uddalaka said.

"As a man from Gandhara, blindfolded,
Led away and left in a lonely place,
Turns to the east and west and north and south
And shouts, 'I am left here and cannot see!"
Until one removes his blindfold and says,
'There lies Gandhara; follow that path,'
And thus informed, able to see for himself,
The man inquires from village to village
And reaches his homeland at last-- just so,
My son, one who finds an illumined teacher
Attains to spiritual wisdom in the Self.
There is nothing that does not come from him.
Of everything he is the inmost Self.
He is the truth; he is the Self supreme.
You are that, Shvetaketu; you are that."

-From the Chandogya Upanishad 6