Answer:
What can be measured but not seen?
My first is a creature whose breeding is unclear. My second, a price you must pay. My whole can be found in the river of Time and refers to events of today.
The stack just might be sent all over. Full of what's new, yet it's nearly obsolete.
I drive men mad for love of me. Easily beaten, never free.
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help. Yet many people are afraid to let me help them.
If lightning strikes an orchestra who is the one most likely to get hit?