nonsense16

I take a matchstick out of the matchbox and light it.
Why?
I do not smoke, nor do I need a light.
When the fire dies, I put the matchstick back in the match box.
I take another matchstick and light it.
When the fire dies, I put the matchstick back in the match box.
Gradually all burnt matchsticks, replace all good matchsticks;
The matchbox with all burnt matchsticks
Remains in my hands as valuable as my life!