some essential questions

Nachiketa

Teach me That you see as beyond right 

And wrong, cause and effect, past and future.

Yama

...

The all-knowing self was never born,

Nor will it die.  Beyond cause and effect,

This Self is eternal and immutable.

When the body dies, the Self does not die.

If the slayer believes that he can kill

Or the slain believes that he can be killed,

Neither knows the truth.  The eternal Self

Slays not, nor is ever slain.

Hidden in the heart of every creature 

Exists the Self, subtler than the subtlest,

Greater than the greatest,  They go beyond

All sorrow who extinguish their self-will

And behold the glory of the Self

Through the grace of the Lord of Love.

...

When the wise realize the Self,

Formless in the midst of forms, changeless

In the midst of change, omnipresent

And supreme, they go beyond sorrow.

The Self cannot be known through study

Of the scriptures, nor through the intellect,

Nor through hearing discourses about it.

The Self can be attained only by those 

Whom the Self chooses.  Verily unto them

Does the Self reveal himself.

...

~ The Katha Upanishad (8th-6th century BC)

as translated by Eknath Easwaran

The Katha is a story which beautifully brings together a confrontation

 of the ideal student with the ideal teacher, leading to a highly creative

 and naked consideration of the key questions: "Who am I?" "What dies?" 

"What is left?" and "what, if anything, can we say about death

 - now, while we are alive?