Answer:
I have a tongue, but do not talk. I follow close, but neither run nor walk. Coupled and hitched, but never married. You couldn't bear the load I've carried.
Hard to catch, easy to hold. Can't be seen, unless it's cold.
A dagger thrust at my own heart, dictates the way I'm swayed. Left I stand, and right I yield, to the twisting of the blade.
What goes through the door without pinching itself? What sits on the stove without burning itself? What sits on the table and is not ashamed?
What I am filled, I can point the way. When I am empty. Nothing moves me. I have two skins. One without and one within.
What is so fragile that saying its name breaks it?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?