The Katha Upanishad is about the deathless Self. It asks the question why do we die? What happens after death? What is left? And who am I anyway? I love the translation by Eknath Easwaran in The Upanishads.
In this Upanishad it says that through meditation one can begin to know the Self and rare are those who follow this path. It is a choice that must be made at every moment.
"The joy of the spirit ever abides,
But not what seems pleasant to the senses.
Both these, differing in their purpose, prompt
Us to action. All us well for those who choose
The joy of the spirit, but they miss
The goal of life who prefer the pleasant.
Perennial joy or passing pleasure?
This is the choice one is to make always.
Those who are wise recognize this, but not
The ignorant. The first welcome that leads
To abiding joy, though painful at the time,
The latter run, goaded by their senses,
After what seems immediate pleasure."
Mayama
Don