For a living being the most fascinating enigma is the phenomenon of life. As he himself is entrapped in the phenomenon he finds it extremely difficult to understand it clearly. Detachment is a necessary condition for clear understanding. But life is something to which man clings on with desperation and knowledge about the true nature of life eludes him.
This subtle nature of life is brought out in the verse that serves as an introduction to Kathopanishad. A free translation of the Sanskrit verse is given below.
It is the divine spirit
That dwells in a cavern of subtlety
That contains all mortal beings.
It sprints like a restless horse
Even while anchored
In a haven of sensibilities.
The spirit of life
Wanders from form to form
Carrying with it
The residues of karmas.
It never dies
And continues in various forms
That were offered to it by nature.
It moves in and out
Imposing its subtle governance
On forms that host its presence.
Knowing it is to be with Brahman."