It is totally free but priceless.
You can't own it but you can use it.
You can't keep it but you can spend it.
And, once you've lost it, you can never get it back.
What is it?
Answer: Time.
See then that ye walk circumspectly, not as fools, but as wise, Redeeming the time, because the days are evil. Ephesians 5:15-16
