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.
What is that which, though black itself, enlightens the world without burning?
I am never quite what I appear to be. Straight-forward I seem, but it's only skin deep. For mystery most often lies beneath my simple speech. Sharpen your wits, open your eyes, look beyond my exteriors, read me backwards, forwards, upside down. Think and answer the question...
Whoever makes it, tells it not. Whoever takes it, knows it not. And whoever knows it wants it not
Often held but never touched. Always wet but never rusts. Often bits but seldom bit. To use it well you must have wit.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?