Answer:
Die without me, never thank me. Walk right through me, never feel me. Always watching, never speaking. Always lurking, never seen.
What can be measured but not seen?
Many have heard it, but nobody has ever seen it. It will not speak until spoken to. What is it?
I open wide and tight I shut, Sharp am I and paper-cut fingers too, so do take care, I'm good and bad, so best beware.
Fatherless and motherless. Born without sin, roared when it came into the world. And never spoke again.
A cowboy rode into Friday. He stayed in town for three days and rode back on friday. How is that possible?